D&D 5E [Let's Read] Dr. Dhrolin's Dictionary of Dinosaurs



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When it comes to various mighty and dangerous life forms, there are few RPGs with bestiaries as large as Dungeons & Dragons’. Dinosaurs are naturally present, and the game hewed closely to pop culture tropes in detailing the most well-known ones such as the tyrannosaurus rex and pterodactyl, often placing them in remote corners of settings mostly unknown to the rest of the world. The Isle of Dread is one of the classic older modules featuring them, but the more recent Tomb of Annihilation adventure featured them prominently as creatures that could be encountered in the rainforests of Chult.

But like many things, D&D only scratches the surface of the vast and fascinating field of Earth’s dominant life form before the rise of humanity. Dr. Dhrolin’s Dictionary of Dinosaurs is a bestiary written by paleontologists who sought to bring scientifically credible rules for such creatures, while also giving advice and ideas for how civilizations of fantasy worlds and the magical energies in various settings may interact with them. While the bulk of the book focuses on dinosaurs and stats, there is also material for new playable races, subclasses, and sub-systems such as domestication and customizable howdahs for really big beasts.

Barring the NPCs, every creature detailed in this book is of the Beast type, which merits important notes in how they interact with things such as the Druid’s Wild Shape class feature or spells such as Conjure Animals and Polymorph. In addition to grading the dinosaurs as monsters, I will also point out my opinions on them on the player side of things when appropriate.

Before we dive into the bestiary, the Introduction discusses the authors’ inspirations, modus operandi, and design philosophy. They talk quite a bit about paleontology and related fields, including the scientific method, how fossils are created by nature and later extracted by human technology. For example, they talk about how data about dinosaurs is compiled by a variety of fields, from studies on reconstructed bones and preserved forms indicating physical capabilities, the environment in which they’re extracted from, the use of radiometric dating to narrow down timescales for the occurrence of various fossil groups, all of which combined together reconstructs a hypothetical world and ecosystem in which the dinosaur(s) lived. They do delve into semi-related subjects, such as the ethics regarding fossils obtained without the consent of a nation/region’s inhabitants. Or threats to the field, such as political and religious groups who oppose the theory of evolution or fraudsters who compile fake dinosaurs from various bones known as “chimeras” in order to get fame and clout from supposedly discovering new species.

A lot of this stuff isn’t of immediate use in a Dungeons & Dragons game, and I can see many people glossing over it to get to the meatier content. But it’s clear that the authors have a passion for talking about it, and as for myself I had fun reading it.

On the game design side of things, the authors note that they departed from typical calculations for proficiency bonuses when designing various dinosaurs. This is in order to better tweak stats to be more authentic to how they believed the dinosaurs were like in real life. For example, an otherwise high-Strength dinosaur may not have a high to-hit bonus for its melee attacks if it’s a rather docile and inoffensive creature. While I understand this reasoning, there are times when the modifiers in question seem arbitrary and don’t include reasoning in the text, such as a dinosaur whose passive Perception is different from its Perception modifier. There are even cases where the departure from Proficiency Bonus/Expertise rules is also applied to NPCs.

Additionally, each creature and plant detailed in this book has Optional Magical Rules that give more supernatural abilities to dinosaurs and new uses/hazards for plants. Sometimes these rules alter the Challenge Rating of a creature, usually increasing it by 1, but sometimes they remain unaltered in the case of particularly weak or powerful dinosaurs.


I do have to note one criticism encountered so far. I have the PDF version of the book, and these two-page spreads don’t line up perfectly in Adobe Acrobat. If you pick the option to show two pages side-by-side, it will only include one half of the spread and the page of the first/last chapter depending on whether the artwork begins or ends. Due to this, I cannot see the two-page artwork naturally unless I screenshot and manually upload the individual pages like I’m doing for this review. Edit: I found a way to have both pages line up together on Adobe, and am uploading new contiguous versions!

As dinosaurs aren’t necessarily an omnipresent element in many D&D worlds, the book discusses ways of including them and related phenomena for campaigns via various story/place ideas. The first, Necromancer Island, involves an alliance of powerful necromancers bringing dinosaurs back to life via fossils, with each necromancer’s private island specializing in a certain type of dinosaur or geologic era. The Ancient Plateau is the second idea, an isolated region full of dinosaurs cut off from the rest of the world via sheer cliffs, powerful winds, and possible magical barriers. The Mad Chronoficer involves an NPC with the ability to travel through time, allowing them to bring long-extinct creatures into the current timeline or transport the PCs to ancient eras. The final idea, the Hollow World, makes it so that the center of the planet is an entire miniature world sealed off by a giant prismatic crystal. The book mentions that one of the official 5th Edition settings “explores this narrative in more detail,” but I don’t know which one that is. I know that Mystara has a hollow world, but that hasn’t been officially updated to 5e.

This chapter ends with two new NPCs. The first is the Chronoficer, a CR 5 spellcaster who has a variety of different spells, including “Stop Time.” Which I presume to be Time Stop. They have other unique abilities, such as treating any d20 roll they make as a 10 three times per day or the ability to create a temporal rift once per day or “as narrative permits” that can be traversed to visit another time period. They are mostly a non-offensive utility NPC, with none of their spells being directly damaging save Catapult, and their primary attack is a pistol that deals necrotic damage.

The other NPC is Dr. Dhrolin, the namesake of this book and a famed dwarven paleontologist. Much of the book contains in-character italicized text detailing the dwarf’s journeys through strange lands, which all began when he was hired to investigate strange happenings in a city’s noble district that soon found himself journeying through time. In terms of stats, Dr. Dhrolin is a CR 2 hybrid melee fighter/spellcaster with a good amount of skill proficiencies. He also has two magic items on his person, a Ring of Fire Resistance and a +3 war pick known as Trusty Rusty that grants advantage when fighting creatures made of earth and stone and can be used as an arcane focus.


Unlike other bestiaries, this one isn’t purely alphabetical. This chapter focuses on four well-known regions and the dinosaurs which inhabited them, and the chapter afterwards details “the Rest of the Alphabet.” Each dinosaur entry includes real-world details such as ecology and behavior as well as annotated sources for further research and its phylogeny in relation to similar organisms. This is in addition to the base stats and listed region types in line with 5e environments, along with the more speculative “how they’d operate and be regarded in a fantasy world” thought experiments.

The first region is the Yixian Formation, named after a rock discovered in China dated around the Early Cretaceous period. Unlike other environments at this time which were warm and humid, the Yixian Formation was much colder, dominated by conifer tree forests, volcanic mountains, and nearby lakes sometimes emitting poisonous gasses. The violent, blazing cycles of volcanic eruptions and suffocating lakes created plenty of fossils, and forests that were destroyed by lava flows would quickly regrow due to the fertile soil. The book presents rules for treating the Yixian Formation as an adventuring environment, such as a d6 table of volcanic events ranging from ash-filled skies to violent eruptions, determining whether lakes are safe or have some kind of hazard, and common flora. The flora’s Optional Magical Rules indicate new uses for harvesting them and there’s brief discussion on what they would’ve tasted like or been used for if human(oid)s lived alongside them. An example is the Khitania columnispicata, whose fruit is a good source of nourishment and its bark would be useful in making ropes, and for magical rules it can be crushed into a paste to grant resistance to cold damage for 24 hours or its seeds eaten to grant immunity for 1 minute.

Each region more or less follows this standard, which really helps to showcase not just the dinosaurs themselves, but what kinds of environments they would’ve lived in and the threats and opportunities present.


Beipiaosaurus is our first dinosaur, a small herbivorous feathered biped with sickle-like claws who likely lived in communal groups and is theorized to have been a slow, sedentary creature who can become fierce if their nest is threatened. They’re slow-pokes with a normal speed of 15 feet and a climb speed of 10 feet, and their slow metabolism gives them advantage on saves to avoid the poisoned condition but said condition’s duration is doubled should they fail. Their primary offensive features are their slashing claws which can deal additional damage if a struck target fails a Constitution save, and the sudden change from their peaceful aura can impose the frightened condition on enemies who fail a Charisma save. Their Optional Magical Rule increases their CR to 3 and unleashes their predatory ancestral instincts by night, where they gain a variety of features such as much faster movement speeds, darkvision, and resistance to non-magical physical damage. But they gain vulnerability to radiant damage and “aversion to bright light,” which I presume is meant to be similar to the Sunlight Sensitivity of drow and similar monsters unless it’s entirely flavor text.

Player-Facing: Their CR is too high for anyone besides a Moon Druid to Wild Shape into. In comparison to other monsters of its CR it is too slow to be a good pick for its CR range, as the Saber-Toothed Tiger and Giant Constrictor Snake have abilities to ensure that foes won’t just Disengage and kite the druid. As for its Optional Magical Rule, this makes it a more decent pick, albeit the Ankylosaurus is the same CR and a much better offensive option that doesn’t require nightfall to be effective. Its Intelligence is low enough to be affected by Animal Friendship.


Bolong is a herbivore who primarily feeds on plants and decomposing wood low to the ground. They had strong tails and thumb spikes they could use to fend off predators and rival Bolong, and are believed to be communal animals similar to cows. They are a CR 4 creature who have a very high passive Perception of 16 despite not being proficient in the skill, and their primary offensive capabilities are either using their Crushing Bulk which deals more damage when they charge (but also deals damage to them) or Thumb Gouges which they can also use as a reaction when hit by a melee attack. In a herd, one Bolong will attempt to distract attackers by fighting to the death while the rest flee. Their Optional Magical Rule doesn’t change their CR, and includes resistance to fire damage along with a rechargeable pseudo breath weapon that has them spit burning ash that creates hazardous damaging terrain.

Player-Facing: Another Moon Druid only Wild Shape, the Bolong is pretty sturdy in comparison to an elephant of the same CR. It has higher AC (15 vs elephant’s 12) and hit points to boot (102 vs 76), albeit its melee attacks are even weaker. The Bolong’s charge attack deals damage to itself and doesn’t knock the enemy prone, making it a worse option to the elephant’s trample. The stegosaurus is the same CR and only has a bit more HP than the elephant, but its tail attack deals a lot more damage while also having reach. The magical variant’s rechargeable breath weapon may be nifty and enough to save the Bolong, as its recurring damage deals 3d6+3 fire damage per round which over a minute can add up to a lot if enemies can be trapped in it. Its Intelligence is low enough to be affected by Animal Friendship.


Microraptor is a four-winged dinosaur that eats whatever it could find and primarily lived in treetops from which it glided between. It’s presumed to be intelligent for its size, and in a fantasy world would’ve likely been curious to the presence of people, using them to distract prey and can possibly be tamed by them. It is a 0 CR creature, putting it in line with various small nigh-harmless animals. It has a climb and fly speed which are slow, but its climbing speed is tripled when it uses the Dash action and has a similar ability to Evasion where it takes no damage instead of half when making a Dexterity save vs damaging effects. Its Optional Magical Rules don’t alter its CR, and grant it the ability to raise its AC by 2 for one turn twice per day via iridescent feathers, and can be taken as a familiar via the Find Familiar spell.

Player-Facing: In regards to straight combat it is a poor choice, like every other CR 0 creature. For flight and scouting the hawk and owls are superior choices in speed and sense (advantage on visual Perception plus darkvision). As for its use as a familiar, it’s still beaten out by the Owl’s Flyby Attack + Help combo. Barring that cheesy combo it’s overall weak for a familiar, but given that such creatures aren’t very powerful in the first place it can be taken for flavor reasons without feeling like a bad option. Its Intelligence is too high to be affected by Animal Friendship, but since you can get it as a familiar you can still choose it as a buddy if you’re the right kind of spellcaster.


Psittacosaurus is a small bipedal herbivore that most likely primarily fed on undergrowth and organized into highly social herds and laid their eggs in creches. The book says they’d be the dinosauric equivalent to sheep, and unlike other Ceratopsians it lacked any kind of horns. They’re also notable for having inhabited large portions of Asia for 24 million years, creating a huge amount of fossils across time periods which are virtually unheard of for other vertebrates. Scientists could even use their fossils to reliably date rock formations.

As a monster it is a CR ¼ creature that has a Proficiency Bonus of +1, a value that is more or less unique to this bestiary. In addition to a snapping beak, they have quills on their back which can be used as an action in melee and also as a reaction counterattack when hit in melee. In groups of three or more they have a Group Sentinel who has advantage on Perception checks, and ranged attacks against them have disadvantage while three or more are within 20 feet of each other. Its Optional Magical Rule doesn’t change its CR and grants them an AoE quill spray attack that deals a low amount of damage in a 10 foot cone.

Player-Facing: For a Wild Shape or Polymorph option they’re pretty weak, and they have no particular special movement modes or senses besides darkvision for scouting purposes. But as an option for Conjure Animals, they can be a good option to lock down melee characters. They can potentially attack up to twice per round with a default attack and reaction-based counterattack, they have hit points and AC roughly equivalent to wolves, and imposing disadvantage on ranged attacks made against them effectively gives them +5 AC to such attacks. That being said, I do feel that wolves win out in having a slightly higher walking speed (40 feet vs 30), and Pack Tactics plus a bite attack that can knock down creatures make for great combos. Its Optional Magical Rule alters things a bit, as switching to a short-range AoE can potentially increase the total damage they do per round by bypassing enemy AC, provided that said enemy isn’t particularly agile. Its Intelligence is low enough to be affected by Animal Friendship.


Yutyrannus is the final dinosaur of the Yixian Formation, being a feathered tyrannosauroid and all that entails. Although smaller than the T-Rex, it is still the largest known creature in the Yixian Formation. They reared their young well after birth and there are indications that they were group hunters. The book suggests that they act like dominant predators in their environment, capable of pursuing prey across long distances and hunt the most during winter when times are leanest.

In terms of stats, they are Huge CR 10 beasts that fight a lot like the tyrannosaurus: get in close, then rip and tear! They have a higher Proficiency Bonus than their CR usually has at +5, can multiattack and have a variety of offensive options beyond just biting, such as claws and a Downy Shoulder Bash that can knock enemies prone if they charged beforehand and make a claw attack should they knock down their target. Their thick coat of feathers grants them immunity to cold damage and resistance to non-magical bludgeoning and slashing (but not piercing) damage. To reflect their status as uncontested predators they have advantage on Wisdom and Charisma saves, and once per day can bellow as a bonus action to call two additional Yutyrannus to be “summoned.” Dinosaurs summoned this way can’t summon on their own so as to prevent an “infinite monster glitch.” Characters who shapeshift into this monster have an altered version of the bellow where they cause friends, family, and other party members to “become aware of the conflict.” This is really vague IMHO; are they merely aware their ally is in danger, or do they know exactly where they are fighting?

Finally, the Yutyrannus has Legendary Actions, which are non-offensive but include granting advantage on attack rolls against creatures provided one of their kind is within 10 feet of said creature, and can make a Perception check (advantage against wounded creatures) to search for hidden creatures. The Optional Magical Rules increase its CR to 14, granting them 2 Legendary Actions per round instead of 1, an AoE cold breath attack, and can Frenzy as a Legendary Action which lets them move 5 feet and make a claw attack.

Player-Facing: Player-Facing: Barring Shapechange or Polymorph cast by a 20th level caster, no PC is going to be able to turn into a Yutyrannus. And at that level, there’s likely a bunch of more powerful choices to pick from which means such an option is more to look cool than pure optimal choice. Their Intelligence is too high to be affected by Animal Friendship. As there are no Beasts that go higher than CR 8 in official rules, the yutyrannus has no comparative creatures at its tier. It’s basically a beefier, heavily-armored, faster t-rex with immunity to a common energy type and advantage on a common saving throw. Pretty much everything good about that monster is exemplified with the yutyrannus. Their Intelligence is too high to be affected by Animal Friendship.

Thoughts So Far: First off, the writers did more than their due diligence when it comes to paleontology, covering their field in ways casual readers can understand but also communicating important facts about the dinosaurs and their geographic terrain without getting verbose. It is far from a light read given its page count, but I found myself clearing as many as 60 pages in a single reading at times. The referenced sources not only include books and articles but also relevant page numbers, making it easier for those who wish to learn further about the aforementioned dinosaurs. The thought experiments and plot ideas for incorporating dinosaurs into fantasy worlds are neat and interesting, albeit rather brief and likely of limited use in only scratching the surface of things. Introducing time travel into a campaign opens up a whole can of worms beyond new creatures, for instance, but I can’t complain too much given the book’s focus and how creative Dungeon Masters can be.

When it comes to the dinosaur stats, the ones in the Yixian Formation are rather weak CR-wise barring the Yutyrannus. They have the inherent limitations of non-magical beasts in more or less having melee only attacks, plus no real defenses against high-mobility ranged attackers or various kinds of magic. The only one that can fly will get one-shotted by almost anything else in the game. The Optional Magical Rules are pretty cool and provide a few workarounds for such limitations and add some more interesting tactical options, such as the Bolong’s ranged fiery spittle. The Yutyrannus is rather deceptive as a CR 10 monster, in that it is effectively three monsters of its kind in one.

Join us next time as we explore the Bahariya Formation and Hateg Island regions!
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Note: Quite a few dinosaurs in this book don’t have one size category, instead listing two. This is likely due to the fact that a few dinosaurs only have juvenile fossils discovered so far, meaning that more accurate surveys of their average size are harder to determine. The Yixian Bolong is the only one noted in that section this way: a Medium or Large Beast, specifically, but the dual-size categories become much more common going forward in this book.

The Bahariya Formation is set in Early Cretaceous Egypt, specifically the Western Desert. It is a region of extremes, veering between hot dry seasons marked by wildfires in scrublands and violent monsoon storms during the wet season, with the soil rich in nutrients for mangroves and other plants to thrive. In spite of all these plants, it didn’t have as many herbivores comparatively speaking, instead having more common carnivorous animals feeding off of the fish, crustaceans, and other aquatic life forms living in the waters. It is a dangerous place for adventurers to explore, with flesh-craving dinosaurs roaming for their next meal on the banks, while the scrublands are prone to fire in the dry season. And in the monsoon season, storms are common as the waters rise, provoking animals to flee for higher ground.

Interesting flora that can be found here include the Marsilea sp* fern that floats on the top of water, whose components could be either made into nourishing food or toxic parts (magic rules allow it to be brewed into potion that grants advantage on Dexterity saves for 24 hours, but the poison can inflict psychic damage), the Agathis sp Evergreen tree that is more than twice the height of even the largest sauropod** dinosaurs (magic rules indicate that the souls of druids often inhabit these trees, and using Speak with Plants to engage in a ritual with them grants advantage on all saves for 24 hours), or the Cladophlebis sp fern that grows on moist ground that can be baked into various edible substances (magic rules indicate it can be baked into flammable oils and grenades to deal bludgeoning and fire damage to targets).

*The “sp” is a scientific term indicating that researchers know the proper genus of a specimen, but cannot determine exactly which species it is.



Bahariyan Polycotylid is a plesiosaur that lives in freshwater environments with specialization in shallow waters. Its long jaw helps it snatch animals on the shoreline, to say nothing of fish and other underwater creatures. It is quite small as far as aquatic dinosaurs go (Medium or Large), indicating that it is likely a more cautious predator who relies on hit and run tactics and will only attack humanoids who interfere with their feeding spots and breeding grounds. In terms of stats it is a mobile CR 5 monster, having advantage on Dexterity saves and checks of various kinds while in water, and can multiattack with bite and paddle slap attacks. It can also use its paddles to stir up an underwater dirt cloud, causing an AoE heavily obscured blinding area. Its Optional Magical Rule increases its CR 6 to and grants it 40 feet of blindsight.

Player-Facing: Like sharks and octopi, aquatic creatures are highly situational when it comes to choosing them for shapechanging and summoning spells. It’s competing with Giant Crocodile and Giant Shark for creatures of its CR, and it falls short of the Shark which has more hit points, a more damaging bite attack, faster swim speed, and has blindsight by default. The ability to create the equivalent of nonmagical darkness spells but underwater may be useful for line of sight and battlefield control, but as the party is likely Tier 3 by now they probably have better means of foiling enemies. Its Intelligence is low enough to be affected by Animal Friendship.


Carcharodontosaurus is one of the largest theropod dinosaurs known, and much like the Tyrannosaurus Rex it is a big carnivorous biped with a powerful bite. While it shares territory with the spinosaurus, their different diets mean that they don’t compete with each other for food and are thus less likely to come into conflict. It is a Huge CR 10 beast with a notable resistance to non-magical slashing damage, advantage on attack rolls against Large to Gargantuan sized creatures, and can make three Ripping Bite attacks which can inflict a new condition known as Torn. Torn is basically what you’d call “bleeding” in other RPGs, where every round in combat or minute outside combat the target must make a Constitution save or take slashing damage. The condition is a tad harder to cure, requiring either 25 hit points worth of healing, a DC 18 Medicine check, Lesser Restoration, or doing nothing but long resting. It also has one use of Legendary Resistance, and its Optional Magical Rule increases its CR to 12, granting it the ability to pick from a random table of Mutations listed later in this book and can spend a Legendary Action to replace one of its mutations with a new one.

Player-Facing: Much like the Yutyrannus, this is a monster whose stat block PC won’t get to use themselves until the highest levels of play. The creature is rather one-note in comparison to the Yutyrannus, mostly being chomp and bite but it has the potential to really wear down foes’ hit points with a combination of Multiattack and a nasty new condition. It is faster than the T-Rex and Yutyrranus, having a 60 foot speed in comparison to their respective 45 and 50 foot speeds. It is too smart to be affected by Animal Friendship.


Paralititan is a sauropod, those famous long-necked dinosaurs are the largest known land animals. The Paralititan is an herbivore like the rest of its kind, and is large enough to not fear most predators. Such creatures often prey on their young and in numbers rather than going after adults. The creature notably includes a new size category carried over from 3rd Edition, being either Gargantuan or Colossal, and is CR 10. It is so large that it is immune to non-magical bludgeoning, piercing, and slashing damage from any source smaller than Huge, and is also immune to the Frightened and Prone conditions while also having advantage on saves vs paralysis and poison. Its Achilles Heel is that it automatically fails any Dexterity save. The Paralititan’s major offensive capabilities include a bonus action Bellow that can cause an AoE frightened effect on non-Paralititans, or a Multiattack where it can do two Huge Stomps that damage and can knock prone a target who fails a Strength save. Finally, it can Rear Up as an action, and then use an Almighty Stomp on its next action that can hit up to two targets who are automatically knocked prone, and as a result of said attack it delivers an AoE prone condition to further targets who fail saves from the shockwave. The Optional Magical Rule increases its CR to 11 and grants it the ability to summon storms when it bellows, calling down lightning strikes on itself and nearby targets. As it has resistance to lightning damage even in its base stat block, this is more of a small price than a risky gambit for the dinosaur.

Player-Facing: Player-Facing: The paralititan is yet another dinosaur with no official Beast matching its CR. Once again it’s a decent choice, but unlike the Yutyrannus of the same CR it requires more setup to use effectively, making it a slightly worse option IMO. It's really slow at 15 foot walking speed, and while its Almighty Stomp deals a lot of damage it requires giving up a round’s worth of actions. The real value is in its outright immunity to non-magical damage from non-big sources, which depending on the encounter can be an immense boon. Just imagine sending this creature to assault an enemy fortification as arrows uselessly bounce off of it. It may be at risk from siege weapons, however. It can be affected by Animal Friendship.


Spinosaurus is a dinosaur whose various physical functions have been debated by paleontologists, and it was only in recent times that new fossils shown more variations in its proportions. The animal has been constructed in a variety of ways, and the stat block’s capabilities in the book reflect the most recent discoveries. The spinosaurus was a carnivore who specialized in hunting fish, although it was likely able to feed upon terrestrial animals and scavenge carcasses as alternative food sources. It is a Huge CR 7 creature who can multiattack with a snapping jaw that can grapple targets and a hooked claw that can push a target 5 feet in any direction. It can also use a reaction when hit by an attack or save-provoking effect to gain immunity to fire or cold damage for 1 turn due to thermoregulation, and when underwater it has blindsight and can hold its breath for half an hour. Its Optional Magical Rule increases its CR to 8, where each time the players encounter it it will have a new feature representing a dramatically different anatomy, such as increasing its base 14 AC to 20, or doubling its walking speed to 60 feet but removing its 30 foot swim speed.

Player-Facing: Its Challenge Rating is just a smidge too high for the Moon Druid’s Wild Shape, but it is still a polymorphable option. As a CR 7 monster it’s competing with a Giant Ape (CR 7) and Mammoth (CR 6). The spinosaurus has a higher AC than either of them, but its 128 hit points fall short of the ape’s 157. Unlike either it has a swim speed of 30 feet, and in regards to its attacks it has no ranged attack (ape can throw a rock) but its snapping jaw deals more average damage than the ape’s fist, with the hooked claw being about on par. It can deal a lot more damage than the mammoth as that animal cannot multiattack. As the spinosaurus’ attacks also impose additional things, it’s a good battlefield control option. Due to this, the dinosaur is a pretty nice Polymorph option. Its Intelligence is too high for Animal Friendship.


Stomatosuchus is a dinosaur that closely resembles a crocodile, although as only one fossil of it was discovered not much is known about the animal. The absence of conical teeth causes researchers to assume that it fed primarily on plankton, but some suggest that it can use its jaw and thin teeth to trap prey. The book goes with the latter interpretation, noting that plankton-based filter feeding requires very specific feeding structures. Its stat block is a Large or Huge CR 4 creature, and predictably it has a higher swim speed than walking speed at 30/20 feet. Its immune system is similar to crocodiles, granting it resistance to poison damage and immunity to the poisoned condition. Underwater it can hold its breath for half an hour and has advantage on Stealth checks, which slightly helps its meager +2 bonus on said skill. It can Multiattack with a bite and tail swipe, and it can swallow small and tiny creatures bitten which are restrained and take further damage in its throat pouch. In terms of tactics the Stomatosuchus won’t attack Medium and larger creatures save in self-defense or in defense of its feeding grounds. Its Optional Magical Rule doesn’t alter its CR, instead giving it a 1d6 table of random magical treasure it swallowed which in turn can give it a specific ability. For example, a holy symbol grants it resistance to radiant damage, while a wand shard can let it cast a damaging cantrip.

Player-Facing: As the Stomatosuchus isn’t as damaging as a giant scorpion’s poison or stegosaurus’ tail even with Multiattack, its major feature is its restraining swallow. While it doesn’t impose the Blinded condition, one could argue that a creature trapped inside breaks line of sight to everyone else, which can be a good way to shut down enemy spellcasters. Unfortunately it only works on Small and Tiny opponents, which greatly limits its usability. Its Intelligence is low enough to be affected by Animal Friendship


Hateg is a landmass peculiar for housing fossils of dinosaurs who were significantly smaller than other specimens found elsewhere. This is known as insular dwarfism, where animals on islands evolve to smaller sizes in order to adapt to the limited resources. Hateg Island is believed to either be a single island, archipelago, or “tiny spit of land” as the book puts it. I don’t exactly know what that last part means, and how that differs from a tiny island. In spite of its small size Hateg Island was dominated by subtropical forests and was very biodiverse, containing all sorts of animals. As an adventuring location it has a unique magical property where any creature from outside who steps upon the island shrinks by one size category over the next long rest. The effect reverses if they get off the island within two days, otherwise it’s permanent.

The unique flora of Hateg Island tends towards the tropical, such as the Pandanites trinervis shrub with fibrous spiky leaves that are sharp enough to cut skin and likely could’ve been made into a curry (magic rule has it where consuming the fruit deals fire damage but grants the eager the ability to breathe fire as a breath weapon a limited number of times), the Ettingshausenia onomasta tree whose wood is sturdy enough to have practical applications for construction (its optional rule causes fibres to erupt when it’s cut down, transforming nearby creatures into Sharovipteryx dinosaurs [small harmless creature detailed later in this book] for 10 minutes), or Phyllites sp ferns that grow in shady areas (magical rules cause it to ooze milky fluids that cause those it comes into contact with to gain vulnerability to radiant damage for 24 hours).


Balaur is the first Hateg dinosaur, named after a dragon from Romanian mythology. It is a Small flightless creature with sickle-like claws on their feet, and its incomplete fossil makes reconstructing its form quite challenging. It could be either herbivorous or omnivorous, and many aspects of it are still under debate. As a creature it is CR ½ and suited to being an ambush predator, with 40 foot walking speed, advantage on Stealth check, darkvision of 60 feet,* can jump up to 30 feet, and is immune to falling damage. It can give an allied Balaur advantage on attacks and saving throws for 1 turn as an action, and its sole offensive feature is using its claws that can damage and grapple foes who fail a Strength save. Its Optional Magical Rule increases its CR to 1 and causes them to revive into a ghostlike form, gaining full hit points and dealing necrotic damage with its claws. This only triggers if it used its advantage-granting ability on an ally, representing them sharing the same spirit.

*The only dinosaur with this in the Bahariya Formation.

Player-Facing: For shapechanging purposes it is competing with apes, crocodiles, and warhorses. Its HP and AC are more or less the same as all three of these creatures, but it has better Passive Perception and Stealth bonuses. Combined with their huge jump speed they are quite good for scouting. Its melee attack is slightly weaker than the aforementioned animals in terms of average damage, and the crocodile’s grapple is harder to escape. On the plus side they can easily hit low-lying flying targets who are up to 30 feet off the ground and don’t have to worry about falling damage when striking them this way. But if you’re wild shaping into an animal to sneak around, there are better options for pure stealth. Due to this, the Balaur is rather okay as a CR ½ choice. Same for Conjure Animals, but their CR 1 magic bump generally isn’t worth it IMO. They’re too smart to be affected by Animal Friendship


Hatzegopteryx is this section’s obligatory high-CR “boss” monster. As it could fly to other landmasses, the hatzegopteryx wouldn’t have been affected by insular dwarfism in competing for resources, and at Huge size it would’ve towered over every other creature on Hateg Island as its apex predator. The book recommends playing it as a fearless creature who would regard even humanoids as prey, usually flying in to catch and swallow someone before flying away. It is a CR 14 creature who focuses on hit-and-run tactics, having an impressive 100 foot fly speed,* 25 foot walking speed, and while on the ground it can Multiattack three times with a combination of its beak, ranging from jabbing it as a strong spear-like motion to prone and stun a target or a flurry which only inflicts prone but has a much higher to-hit bonus (+12 vs spear’s +8). It can swallow prone creatures as a bonus action if it has at least 100 hit points, but due to being heavy it can only fly via a Legendary Action (which it has 1 per round) or if it’s falling. Its throat pouch restrains and deals bludgeoning damage to targets, while also slowly suffocating them over the course of 1 minute. For defensive features it is immune to thunder damage,** has one use of Legendary Resistance, and has an Evasion-like feature that can’t be used on attacks originating from swallowed targets. Its Optional Magical Rule bumps it CR to 18, granting it the ability to perform an AoE Sonic Shockwave by increasing its fly speed to 600 feet and moving that distance, can screech as a Legendary Action that can damage and frighten creatures, and gains resistance to both magical and nonmagical bludgeoning, piercing, and slashing damage along with cold, fire, and lightning.

*This speed is reduced by half when it’s carrying swallowed targets.

**I wonder how that works in terms of scientific anatomy?

Player-Facing: Too high CR to shapechange into (its magic version has the highest CR in this book). In addition to being yet another high-level Polymorph option, Hatzegopteryx has an ace up its sleeve in that few creatures can beat a 100 foot fly speed. While that speed is reduced when it swallows creatures, 50 foot flight isn’t anything to sneeze at either. The main problem is that as it can only fly via a legendary action or if falling, a Polymorphed version will somehow have to be launched into the air by another source in order to do so, more or less requiring the caster to cast the spell while dropping from a height. The fact that it can only attack while on the ground makes it a bit situational and weak, albeit it can still swallow prone creatures while flying. The hatzegopteryx is dumb enough to be affected by Animal Friendship, but given its Legendary Action will most likely resist that.


Magyarosaurus is a very small sauropod, being only Large in size. Even at its reduced size most predators wouldn’t have bothered with adults, and the hatzegopteryx would’ve hunted the hatchlings instead. Due to being isolated on an island it likely wouldn’t have been afraid of unfamiliar creatures such as outside explorers, which would’ve made the magyarosaurus easy to domesticate for agricultural purposes. In terms of stats it is CR 4, notable for a crappy -4 Dexterity saving throw but a sturdy +6 Constitution save and advantage on Strength saves of which it has +4. Like the Paralititan it can rear up as an action to deliver a damaging prone-inducing stomp, but otherwise its main attack is slamming with its neck which it can also use as a counterattack reaction when hit in melee. Its Optional Magical Rule increases its CR to 5 and grants it the ability to cast Invisibility twice per day without components.

Player-Facing: Much like the Bolong, this CR 4 dinosaur is competing with other big and beefy animals such as the elephant and stegosaurus. It has the potential to deal more damage in a round than the stegosaurus if it uses a stomp attack (33 damage average) and is followed up by a reaction-based neck attack (15 damage average). But as the stomp requires sacrificing a round and the reaction attack requires getting hit in combat, this still makes them an inferior choice for damage. Their 20 foot walking speed is also far slower than the aforementioned animals, another point against them. Their Hit Points are far higher than other Beasts of its CR at 106, and its 17 AC is far higher than the stego’s 13 and elephant’s 12, which helps save it as being a decent option in terms of sheer endurance and tanking.


Struthiosaurus is a dinosaur noted for its osteoderm armor, which are bony deposits lining its body. It was an herbivore that could use its long tongue to eat plants growing close to the ground. It is a nodosaurid, which along with ankylosaurids is part of the Ankylosauria group.* But the Struthiosaurus’ tail is more flexible than an ankylosaur’s rounded bludgeoning tail. In terms of stats it is CR ½, possessing a decent 22 hit points and a very sturdy 17 AC. Any creature that hits it in melee suffers 1d4 slashing damage, and it can attack by tackling which deals a mixture of bludgeoning and slashing damage. Alternatively it can take up a defensive stance as an action, granting itself resistance to non-magical bludgeoning, piercing, and slashing damage. Its Optional Magical Rules enhance this Defensive Stance with rainbow osteoderms that let it swap one of the damage resistances with any other damage type, and it deals +1d2 damage with its automatic counter damage.

*Figure they could’ve used a more different-sounding name for the latter.

Player-Facing: No other official Beast at this CR has Armor Class this high, which makes it a good choice for a melee attacker. It doesn’t do as much damage as an ape or crocodile, nor is its to-hit bonus that good at +3. Ironically it is better off using Dodge instead of a Defensive Stance: Dodge effectively grants it +5 AC and can thus negate damage entirely rather than halving it. The damage automatically inflicted by attackers isn’t enough to matter save against very weak opponents such as goblins, and its optional magical rule doesn’t really increase its overall effectiveness. It is for these reasons that the Struthiosaurus is a bit of a gimmick option useful mostly for tanking purposes. Its Intelligence is low enough to be affected by Animal Friendship


Zalmoxes is a Small bipedal herbivore part of the Rahbdondontidae, which includes much larger animals. Its discovery on Hateg Island made it the textbook example of insular dwarfism, but a recent study argued that it was average-sized for that group and other Rahbdondontidae evolved to become even bigger. The Zalmoxes is primarily a herd animal who often have sentries to scan for threats. The book suggests that this behavior combined with its stout body would’ve made them easy to domesticate for livestock.

In terms of stats they are CR ¼ but have an awful lot of hit points for this CR at 42. Their AC is still a low 11, and while they have +3 Perception and Darkvision of 30 feet,* their Passive Perception is 1 lower at 12. Their sturdy body grants them resistance to non-magical bludgeoning damage, and while it can attack with a beak it will not attack unless cornered or otherwise trapped, preferring to flee instead. Its Optional Magical Rule doesn’t change its CR, where it lets out a shriek upon reaching 0 hit points, cursing whoever dealt the knockout/killing blow to suffer supernatural cowardice. For the next 24 hours or until magically cured they must make a Wisdom save each time they enter combat, or become frightened of all foes for a minute.

*Another dinosaur with this exclusive sense type for their region.

Player-Facing: Boy howdy, talk about defense over offense! 42 hit points is astounding for a creature of this CR, although its beak attack at 1d6+1 can be done better by creatures such as a wolf or the poisonous animals in this grouping. The darkvision is much shorter than other animals that get it, and its non-magical bludgeoning resistance is too situational to be of much use. It’s an overall poor choice for shapechanging or summoning, and is too smart to be affected by Animal Friendship.

Thoughts So Far: Almost every dinosaur has some interesting ability they can do in combat beyond straight damage, plus the rare non-combat utility feature such as the Balaur’s great leap. This helps set them apart from Beasts in the official sourcebooks, which I like very much. Of the two sections, I like the Bahariya Formation a lot more: it gives us some higher-CR and bigger dinosaurs, a welcome change of pace to the less threatening Yixian group. Hateg Island isn’t as exciting as an adventuring location, as its primary terrain-based hazard seems to be permanent size reduction which feels a bit unimaginative and overly punishing. The dinosaurs of Hateg Island also don’t excite me as much as Bahariya’s, but the inclusion of what is basically a tough, speedy hit-and-run boss monster is a definite high point. The Agathis’ druidic soul magical rule is really cool, and I do like the various herbal creations one can make from the plants. So even with my criticisms these two sections are still a worthwhile read.

Join us next time as we explore the Crato Formation and begin the Rest of the Alphabet!
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I do have to note one criticism encountered so far. I have the PDF version of the book, and these two-page spreads don’t line up perfectly in Adobe Acrobat. If you pick the option to show two pages side-by-side, it will only include one half of the spread and the page of the first/last chapter depending on whether the artwork begins or ends. Due to this, I cannot see the two-page artwork naturally unless I screenshot and manually upload the individual pages like I’m doing for this review.
You can use a PDF editing app to add a blank page at the beginning of the book (or delete a page you don't need!), and then you should get proper two-page spreads when viewing two pages at a time. I use that trick a lot.


Dinosaurs.... My domain. Love this work, incidentally.

Spinosaurus is a dinosaur whose various physical functions have been debated by paleontologists, and it was only in recent times that new fossils shown more variations in its proportions.
Which never ends, incidentally. The artist for this book, Mark Witton, even had a lovely meme up about how things were. There's a reason We don't talk about spino was an immediate hit in the paleo-meme sphere and that is this lovely dinosaur causes nothing but trouble

Stomatosuchus is a dinosaur that closely resembles a crocodile
Stomatosuchus is just a crocodile. Well, not 'crocodile' specifically but its in the croc-line, not the dino line. Outside of modern crocodiles, but still close enough to them that if it was here today we'd basically call it one

**I wonder how that works in terms of scientific anatomy?
Hatzegopteryx is notably a dense pterosaur, to the point when its bone were first discovered they were thought of as dinosaur bones instead. So could be a way to represent the fact this thing is just tough? Best to play them as horrifying just events that occur, of course, because that's basically what we thought Hatzegs were. Just Events that sometimes happened. They are the Pterosaur Overlord of Transylvania for a reason.



Dating around 120 million years ago during the Early Cretaceous period, the Crato Formation is located in northeastern Brazil and famed for having some of the best-preserved fossils in the world. While this has been a blessing for research, it has also made the region a target for black market exports of dinosaur fossils. These operations have become so lucrative that fossils from Brazil can be found all over the world, and has had a negative effect on that country’s own paleontological research and tourism. The authors of this book state their support for the return of illegally-acquired fossils to their home countries.

The specifics of the Crato Formation’s environment is under debate, with some researchers believing that it was a lake-lagoon and others believing that it was a semi-arid wetland. The insects and plants found around the region point to being native in scrublands and freshwater environments. The rarity of fish, combined with higher than normal salinity levels, points towards the lake being mostly freshwater near the surface and saltier near the bottom. In many ways, it was a lush beacon of life in an otherwise dry and inhospitable environment. As an adventuring location, suggested hazards include exhaustion-inducing heat for those who go unsheltered for too long, sudden heavy rainstorms and flash floods, deceptively fresh-tasting saltwater, and the risk of petrification for those who touch the bottom of the lake and fail a Constitution save.

The Formation’s plants are mostly hardy specimens that can survive in very dry environments, such as the leafy Klitzchophyllites flabellatus that grows in shallow water (optional magic rules allow intelligent creatures to speak any language for 1 minute if they place a leaf under their mouth), the Equisetum sp. whose younger shoots are edible but whose adult forms are poisonous (optional magical rules turn it into a plant that can heal or inflict the poisoned condition depending on maturity), and the dangerous to handle Welwitschiophyllum brasiliense with incredibly sharp leaves and an edible central stem that likely would’ve tasted like an onion (magical rule has it so that creatures between Small and Large take 1d4 piercing damage if they are pushed/fall on/run into them, and its stem can be turned into 4 days’ worth of trail rations for a single humanoid).


Cratoavis is our first dinosaur, a Tiny creature that looks a lot like a modern bird. Like many modern birds it primarily feeds on insects but might have subsisted on other foods such as fruits and possibly carrion. Their species was incredibly spread out, existing on every continent save Antarctica before going extinct sometime around the end of the Cretaceous period. In terms of stats they are a CR ⅛ creature with extremely high Perception and passive Perception (+6 and 18), can twice per day do a Charming Display that is akin to Charm Person but encourages the target to give food to the animal, and as long as its flying and moved last turn it increases its AC by 3 (from 13 to 16) and ignores opportunity attacks when flying out of an enemy’s reach. Its Optional Magical Rule leaves its CR intact, where if slain its body will not decay and merely becomes unconscious, capable of waking up via healing magic. Additionally if it charms a PC and is offered food, it will continue to follow the party in hopes of getting more food from them at least once per day.

Player-Facing: The closest comparison of a creature of its CR would be the Blood Hawk and Flying Snake. It has less hit points than either of them (3 vs the hawk’s 7 and snake’s 5) and its primary peck attack is both less accurate and damaging at +2 to hit dealing 1d2+1 damage, and its fly speed is slower at 40 feet. However, the Cratoavis has a stronger version of Flyby Attack, which increases its AC to be higher than either animal. Its optional magic rule can make it quite resilient in spite of its low hit points, and can serve as a clever means for a party druid to avoid certain death if they are facing an unwinnable scenario. Given that at such low hit points there isn’t much difference in survivability, this can make the Cratoavis a good skirmishing enemy for a CR ⅛ creature. The Charm Person can be a good means of battlefield control, particularly if the birds are summoned in groups via Conjure Animal and are used to distract enemies. Its Intelligence is too high to be affected by Animal Friendship.


Ludodactylus is a pterosaur that primarily feeds off of fish, keeping close to most bodies of water be they freshwater or oceanic. They often hunted in packs, but as they’re unable to eat anything larger than Tiny size they wouldn’t be a threat to humanoids unless their nesting grounds are threatened.

The ludodactylus is a CR 3 creature that has a good number of skill proficiencies, ranging from the typical Perception, Stealth, and Survival, but also including Acrobatics, Athletics, and Intimidation. They have advantage on attacks against creatures submerged in water and don’t provoke opportunity attacks when moving out of enemy reach provided that they’re flying. If they’re on the ground they can launch themselves into the air as a bonus action, possibly knocking adjacent targets prone, and its primary forms of attack include a multiattack melee beak bite and projectile vomit that deals acid damage.* While flying it can also snatch and disarm small items held or in possession of creatures by forcing a Strength check on the target. Interestingly plant creatures have advantage on attacks against the dinosaur, for its preserved fossil was discovered to have died from eating a sharp yucca leaf and the wound thus became infected. Its Optional Magical Rule increases its CR to 4, allowing it to be mounted by Small creatures and wear barding, and gains a ranged attack that deals force damage.

*This is one of the few dinosaurs in the book with a ranged attack.

Player-Facing: As none of the core CR 3 beasts have a fly speed, the Ludodactylus is a pretty good choice. Its hit points are a decent 45, its fly speed also 45, and while its ranged attack is a mere 15 feet it should be a decent skirmisher given its Flyby Attack equivalent. The ability to snatch items from targets is a good way of disarming enemies of weapons, spellcasting foci, components, and other valuables. Its Intelligence is too high to be affected by Animal Friendship.


Tetrapodophis is a snake-like creature so small it has its own size category of Miniscule at 8 inches in length. It was initially thought to be a burrowing animal, but recent research discovered comparative physiology with aquatic lizards. It fed on fish, insects, and small reptiles and while not a threat to humanoids it would have bitten in self-defense if antagonized. It is a CR 0 creature that isn’t really good at anything except perhaps hiding (Stealth is at +5), and while in water it gains the equivalent of Evasion and attacks against it are made at disadvantage. Its Optional Magical Rule increases its CR to ½ and gives it a venomous bite that deals poisoned damage, one level of exhaustion, and the poisoned condition. The exhaustion levels top out at 4 from this venom.

Player-Facing: Like most CR 0 animals there isn’t a practical reason to choose it for a shapeshifting or summoning, save for some rare situation where someone has to pass through a small area even Tiny creatures cannot bypass. The magical variant can make for a good debuffer if the animals are summoned in batches and sicced on a single target, and the save DC is pretty decent for its CR: DC 14 in comparison to a giant wasp’s 11 or poisonous snake’s 12. It can be affected by Animal Friendship.


Tupandactylus is a pterosaur that has a huge sail-like crest on its head. As such a placement would not aid in aerodynamics, it is believed that the crest was used for mating purposes as the ones with the largest crests would be viewed as the healthiest. It was probably a forager, scouring nearby woodlands and coming to the Crato Formation’s lake primarily to drink. They aren’t particularly offensive, more likely to flee than fight, save of course when it comes to the defense of their young and prime feeding spots.

In terms of stats it is a CR 2 creature, and like the ludodactylus it has quite the number of skill proficiencies, but with a pretty big +3 Proficiency Bonus and can launch itself into the air and knock prone adjacent targets. It is slightly faster than that creature at a 50 foot fly speed, and also resistant to lightning and thunder damage indicating its willingness to fly even during storms. Its primary means of attacking are a multiattack beak-slash or a Dazzling Display that grants itself advantage on Charisma saves for 1 minute. The Display also functions as a short-range gaze attack that can grant disadvantage on said saves and Charisma skills for an equal duration on a failed Dexterity save. Its Optional Magical Rules up its CR to 3, make it immune to thunder damage, make its beak deal additional damage of that same energy type, and has a rechargeable AoE shockwave attack that deals thunder damage and disadvantage on attack rolls for 1 turn. Amusingly both AoE abilities also impose a disability on the tupandactylus, causing it to take disadvantage on Perception checks for 1 minute.

Player-Facing: When it comes to CR 2 flying creatures, the quetzalcoatlus from Volo’s Guide to Monsters is perhaps the closest equivalent. Sadly the tupandactylus doesn’t compare in offense or speed, where the Volo dinosaur has a speedy 80 feet and Flyby Attack, making it a skirmisher par excellence. The tupandactylus could make for a better scout given its skill proficiencies, but its AoE dazzle is of limited use unless the party has people with Charisma save-targeting abilities. The CR 3 magical powers are probably not enough to save it, due to the short range of its shockwave attack. I should note that this product has an alternative version of the Quetzalcoatlus, albeit as a Huge CR 9 creature instead. So if a DM uses that instead of Volo’s, the tupandactylus may become a better option. Its Intelligence is too high to be affected by Animal Friendship.


“Ubirajara” is a dinosaur whose fossils were taken illegally from Brazil, and this controversy caused the manuscript detailing the creature to be pulled. Thus the name is considered invalid and it thus doesn’t have a formal name yet. It was a dinosaur that was most likely a scavenging predator, and its dense mane of feathers would’ve probably made it look quite fluffy. The book suggests playing it as an alert animal that would keep its distance from most PCs save for injured and weak Small creatures which would register as prey.

“Ubirajara” is a Small CR ½ creature with 30 foot darkvision, advantage on Stealth when in foliage, and can halve any bludgeoning or piercing damage targeting it as a reaction. It also gets a +5 Intimidation on account of its feathery mane. Its sole means of offense is a multiattack nip that hits three times but doesn’t do a lot of damage individually (1d4+1 piercing). Its Optional Magical Rules don’t alter its CR, giving it a 30 foot range filamentous spear attack that can’t multiattack, and once per day can open a portal that leads it to wherever it considers home in the Multiverse. Other creatures up to Large size can follow it through the portal for the next minute.

Player-Facing: As a CR ½ creature its closest comparison would be the Ape. Even with 3 attacks the Ape wins out in overall damage, and the “Ubirajara” has a slow 25 foot speed which means a lot of other animal options can outrun it. Therefore, the creature is most likely to be used as a scout considering its situational Stealth advantage, darkvision, and a surprisingly high Passive Perception at 15 despite not being proficient in the skill. As for its magical bonuses, the filamentous spear is roughly on par with the Ape’s rock attack, but the limited teleportation can be extremely useful in the right circumstances. Trapped in a dungeon? Take the party to safety at the shapechanger’s home! Its Intelligence is too high to be affected by Animal Friendship.


Consisting of 32 dinosaurs unconnected to any particular era or locale, this covers the rest of the Dictionary’s bestiary save for the unique creatures from higher-end backers of the Kickstarter. I will not be covering all of them in this post, instead breaking this chapter up into smaller sections.


Arizonasaurus is a Middle Triassic creature that lived in Arizona back when it was a floodplain. Its most distinctive feature was a large dorsal sail whose primary purpose is under debate, ranging from display for mating purposes, thermal regulation, or making itself look more threatening to other animals. It was a predator who spent much of the day resting in order to conserve its energy, and if its sail was used for thermoregulation it would’ve been multipurpose: blood flowing into it would’ve helped cool it off, while orienting it perpendicular to the sun would’ve helped warm it up in the early morning.

In terms of stats it’s a Medium CR 1 creature, its special abilities including 30 feet darkvision, gaining advantage on Intimidation checks as a bonus action by flushing its sail with blood, and is resistant to either cold or fire damage depending on the time of day. Its primary attack is a bite which can deal additional slashing damage if the target fails a Strength save and also grapples the target if they’re Medium or smaller. Its Optional Magical Rule increases its CR to 2 and grants it a consistent AoE aura dealing fire damage as well as personal immunity to that damage type.

Player-Facing: The arizonasaurus’ main competition is with the Dire Wolf, which has more hit points (34 vs the dino’s 29) and a better AC (14 vs the dino’s 11). The arizonasaurus’ bite attack deals less damage, with the only real upside being a slightly higher DC (14 vs the wolf’s 13) for its mobility-impairing condition. The CR 2 version makes the dinosaur a much better option, as the consistent AoE fire damage can stack nicely with its existing melee attack and the potential to grapple. It’s still fragile in comparison to monsters of that CR, particularly the Giant Elk and Saber-Toothed Tiger. It can be affected by Animal Friendship.


Centrosaurus is a horned dinosaur that is a smaller relative of the triceratops, and exclusively herbivorous in feeding off of ferns and branch leaves. Like the triceratops it lived in herds for protection, and while its horns were effective weapons its frill was quite weak and wouldn’t have protected it against a tyrannosaurus rex.

It’s a Large CR 3 creature that gains +2 AC (base AC 13) whenever it is facing in the direction of an incoming attack,* has advantage on Wisdom saves, and can fill its frills with blood as an AoE gaze-based attack with a bonus action. Those who fail a Charisma save have disadvantage on all saves for the next minute. Its primary attacks are either a horn swipe or a more damaging charge which requires it to first move 20 feet in a straight line. Its Optional Magical Rule increases its CR to 4 and lets it cast Mirror Image once per day without components as a bonus action, and lasts for 24 hours.

*Hope you like facing rules!

Player-Facing: The closest comparison would be the ankylosaurus, which has a better AC at 15 but less hit points (Centrosaurus has 72 vs ankylo’s 68). The centrosaurus’ attack deals slightly less damage, but its real valuable ability is the AoE frill. As it only affects enemy targets there is no need to have allies move out of range first, and the many combinations for disadvantage on saves are self-evident. A 24 hour Mirror Image is an amazing ability, making the Centrosaurus a great choice be it magical or non-magical. It can be affected by Animal Friendship.


Concavenator is most noted for a hump, being an archpredator that lived near a large lake used as a water source for various animals. The hump’s function is unknown and subject to debate, and it likely hunted in groups like lions.

It is a Large CR 3 creature who fights with a very damaging bite and claw attack, which is treated as a single attack but deals two separate instances of 2d6+2 damage. It has advantage on any Strength check to avoid being grappled, and its Mysterious Hump has one of three suggested abilities: advantage on Charisma checks for sexual display, gain resistance to fire or cold damage as a reaction against an attack or save-inducing effect for thermoregulation, or only needs to drink once per month for storing fat. Its Optional Magical Rule increases its CR to 4 and makes it related to the Bulette, granting tremorsense, a burrowing speed that grants it resistance to non-magical damage when so moving, and can burst upwards from underground to gain advantage on attack rolls until the end of its turn.

Player-Facing: In terms of offense the concavenator deals roughly equivalent damage as an ankylosaurus’ tail attack, but has two different damage types. It can’t do as much as a giant scorpion with its poison, and the concavenator is more fragile than the ankylosaurus with a lower AC and hit points. The Mysterious Hump is mostly for defense and utility, more of a situational gimmick. The magical rules granting it tremorsense and burrowing redeems it a bit, particularly for hit and run and scouting tactics. Its Intelligence is too high to be affected by Animal Friendship.


Deinocheirus is the largest example of its various families (gallimimus, ornithomimus, and struthiomimus), being around 36 feet long when fully grown. Its fused spines form a hump or sail running along its back, and combined with likely having feathers all over its body would’ve given it quite the distinctive appearance. It’s primarily a meat-eater, albeit it mostly used its claws for digging into soil to expose small animals which it likely snatched up with its long tongue, and it probably waded in shallow water to eat fish and plants.

It is a Huge CR 6 creature, having a slow swim speed but being able to move in shallow water without reducing its speed or having to swim, and its multiattack claws could also cause creatures to drop wielded items on a failed Strength save as well as dealing additional poison damage if both of them hit, reflecting coating the wounds with mud. The deinocheirus’s long tongue can be manipulate items from a distance. The tongue can also be deployed as a bonus action where it can pick up and wield non-ammunition weapons and attack with them as a bonus action (albeit it is not proficient with such weapons). To top things off, the deinocheirus has advantage on Intimidation and Persuasion checks,* and its Optional Magical Rule increases its CR to 8 by granting it resistance to poison damage and a rechargeable line-based breath weapon dealing poison and bludgeoning damage at 4d8 each.

*Kind of wondering how a non-magical non-shapeshifted dinosaur would use Persuasion.

Player-Facing: The deinocheirus is roughly equivalent to a mammoth in terms of hit points and Armor Class, and while its walking speed is slower it has more maneuverability in watery environments. It can deal a lot more damage than a mammoth, as each claw attack can deal 22 damage on average, plus 1d6 if both hit, and disarm enemy weapons and items. And add on top a bonus action tongue attack with all sorts of weapons, you open up a bunch of options. The deinocheirus may thus be one of the few shapechanged Beasts that can thus wield a magic weapon this way, and while not proficient its 22 Strength should still give it a decent chance to hit. Its CR 8 version is only accessible by Polymorph and similar magic, and thus has to be compared to a Tyrannosaurus Rex. While it still loses out on melee damage and hit points, the AoE breath weapon is a good ranged option that does a decent amount of damage, making it still a good option. It can be affected by Animal Friendship.


Deinosuchus is a relative to modern alligators, appearing much like a far larger version of such animals. Being in the Late Cretaceous, its fossils were found around an inland sea known as the Western Interior Sea, and it was likely semi-aquatic. Deinosuchus was likely a patient ambush predator that could hunt either alone or with others of its kind, and the book suggests that it is fearless and would willfully attack all but the largest of creatures.

It is a Huge CR 11 dinosaur, marked by its extreme resiliency in having resistance to all damage types and immunity to the poisoned condition. This effectively doubles its 155 hit points to 310, and combined with its 18 AC it can last for quite a while in combat. Like alligators it can hold its breath for a long time and has advantage on Stealth checks in water (-1 modifier means it’s still not good at sneaking overall). Its major attack is a Bone-Crushing bite that ignores armour, meaning that it is resisted by a Dexterity save rather than a to-hit roll, and creatures bigger than Medium suffer disadvantage on the roll. It can damage, grapple, and restrain such a struck target. It also has 1 Legendary Action per round, which it can use to either Thrash as a short-range damaging AoE or a Deathroll against a grappled target that deals force damage on a failed Strength save (success halves the damage). The deinosuchus’ Optional Magical Rule makes it worshiped by locals as a regional demigod, who decorate it with various materials. The Deinosuchus will not attack humanoids save in self-defense, and locals offer the creature food to safely pass through its territory…which sounds like a bit of a contradiction.

Player-Facing: Its CR is too high to be an option for Polymorph or Wild Shape. The deinosuchus is an extremely good Polymorph option. So good in fact it may cause a DM to have serious thoughts about banning or restricting it. Its meager 20 foot movement speed makes it ideal to use either underwater (40 foot swim speed) or in closer environments. The bite attack is a particularly great means of dealing a lot of damage to big monsters, given they tend to not have great Dexterity saves in the first place, and effectively having 310 hit points more or less makes it the best option period for tanking. The only time you might use something else is the paralititan if you’re guaranteed to be going up against creatures who don’t have magic weapons, energy damage, or are too big in size. Its Intelligence is low enough to be affected by Animal Friendship, and while it’s proficient in Wisdom saves at a +5 bonus it has no Legendary Resistance to auto-succeed.

Thoughts So Far: Once again, the Dictionary of Dinosaurs gives us more mechanically interesting creatures who are guaranteed to have a trick or two up their scaled sleeves besides basic damage. The practically harmless cratoavis and tetrapodophis aren’t really challenges or even hazards on their own, being more akin to set dressing, so I found them the least interesting overall. My favorite dinosaurs among this post include the centrosaurus for its interesting non-damaging features, the deinocheirus for its weapon-wielding tongue, and the deinosuchus’ bite which is so massive it’s more akin to trying to dodge a fireball. I also liked how the Concavenator had various suggestions for its hump’s use, reflecting how even in the ever-evolving fields of science there isn’t always one certain answer.

Join us next time as we journey further into the Rest of the Alphabet!
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