Antediluvian Beasts of the East Season 2: The Fantastic and the Ferocious

Antediluvian Beasts of the East: Daeodon leidyanus

Draining from the early Miocene Appalachian mountains are the streams and creeks which flow through the woodlands of New Jersey until they reach the blue Atlantic. Fed by mountain lakes and aquifers, these meandering waterways provide a much-needed source of liquid to the parched lowlands of the summer. Flowers and grasses shoot up through the cracked ground as the fluid product of the rainy season in the mountains turns the earth the deep brown and the tree leaves a healthier color. Though the temperature still peaks at over 32° Celsius (90° Fahrenheit), many large herbivores can be found in these coastal forests. Gigantic two-horned semiaquatic rhinoceros settle down into the waterholes of clearings. Three-toed horses race through the woods and munch on tree leaves as peccaries squabble over roots and burrow sites. Extinct distant relatives of modern mouse deer with two horns at the back of their skulls and a branching one at the front of their snouts compete for mates and territory, wearily checking the surrounding trees every few minutes for signs of danger. In the seas, multiple species of gargantuan sharks vie for chow with ancient relatives of sperm whales with gargantuan teeth an jaws as  other species of whales bask and play near the surface, their calls heard for miles. Mollusks scavenge on the sea floor as fish schools swim along.

Back on land, a group of peccaries jog through their favorite mud hole through an open patch of grass and flowers. The size of modern javelinas, these herbivorous mammals are often left to their devices by predators and other herbivores weary of sustaining an injury from the peccaries’ large front tusks. Even the rhinoceros, the largest animals to roam these forests, are weary of the smaller mammals. 

As the peccaries cross the opening in the forest unaware, a huge predator stalks them. The gleaming eyes of this colossus give off the faintest light on the predator’s distorted muzzle. Covered with scars, cuts and the occasional protuberance, it would appear that this creature is of another nature from the other mammals of early Miocene New Jersey. However, it is nonetheless the largest mammalian predator to stalk this forest. This is an entelodont, a relative of the group of mammals which includes hippopotami and whales. However, the grizzly, misleadingly hog-like appearance and terrifying predatory behavior of this odd mammal has given it the more ominous name of “terminator pig”. The massive front teeth of this humongous beast are rooted into its robust, meter-long skull. Its large body, built with powerful shoulder muscles and powerful, hoofed limbs to overpower its quarries, slopes down into a small tail tipped with fur. 

From the bushes, the terminator pig charges at the peccary group, which scatter in fear. However, the large carnivore has outplayed the smaller tusked mammals, and has snagged the belly of one peccary on its canines. As blood loss takes its toll, the panicked ensnared peccary tries at its large attacker with its front teeth, scraping the terminator pig’s chin. The counterattacks are of no help to the peccary, who soon dies in the jaws of the larger mammal. With a single bite, the entelodont devours a large portion of the peccary’s gut, though it will stash away the rest of its kill in a hole created by the roots of a fallen tree which the carnivore inhabits. 

Though the Miocene exposures of the east coast of the United States are more famous for their marine fossils, like those of the gigantic shark C. megalodon and the toothed whale Squalodon, a variety of equally incredible animals roamed the land. Unfortunately, these incredible animals, some of which among the largest predators North America would ever see, have not gotten the attention which they deserve.

One such carnivore, a mammal known as an entelodont, left its fossil mark in Farmingdale, New Jersey in the form of a left premolar and molar named Ammodon leidyanum by the famous paleontologist Othneil Charles Marsh (Marsh, 1893). Though another famous paleontologist, Edward Drinker Cope, speculated that the teeth came from a pig-like creature, more finds in the northwest United States would be needed to reveal the animal’s true identity (Gallagher, 1997).

In the end, the mystery of Marsh’s Ammodon leidyanum was solved. The mammal, now known to be an entelodont, was a large, gruesome predator with large teeth and the occasional bony protuberance off of its lower jaw to create a distinctive-looking skull. These big slashing teeth would have been able to rip into the flesh of the large mammals of early Miocene New Jersey, feeding the meat to the entelodont’s premolars and molars, which would start to grind and crush whatever the predator decided to swallow. Their long muzzles would have connected to a large, robust body supported by relatively thin, hoofed limbs. Among the classic features of the entelodonts were two bony lumps which extended from the skull.

More recent additions to the scientific literature had discussed whether Ammodon was truly a valid genus name for the Farmingdale entelodont teeth. In 1998, a remarkable conclusion as to the identity of the teeth was reached. It would seem that the teeth actually belong to a species of the western North American entelodont genus Daeodon, the largest known genus of entelodont (Lucas, Emry & Foss, 1998). Large individuals of this genus could have the shoulder height the height of a man. The holotype tooth of the Farmingdale creature is slightly larger and longer than the same element in western Daeodon (Lucas, Emry & Foss, 1998), which may suggest that the New Jersey animal was either larger than its relative from the American West or had larger teeth.


The approximately one meter long skull of a western Daeodon at the Denver Museum of Nature and Science. Note the large front teeth. Photo by the author, 2014. 

The entelodonts as a group had evolved to pursue and attack the large mammals which benefited off of the plants of the plains and forests of North America, though they would occasionally chow on tubers and roots to supplement their primarily carnivorous diet. Like modern large mammalian predators, entelodonts were opportunistic, scavenging carcasses on occasion. In New Jersey, Daeodon leidyanum would have been a part of the Farmingdale local fauna of the basal Kirkwood Formation of coastal New Jersey (Tedford & Hunter, 1984; Gallagher et. al., 1995). This assemblage of mammals has yielded the remains of the three-toed horse Anchitherium, the rhinoceroses Diceratherium matutinum and Menoceras, the protoceratid Prosynthetoceras, and the peccary Hesperohyus antiquus (Tedford & Hunter, 1984; Gallagher, 1997), and is likely Arikareean in age (Lucas, Emry & Foss, 1998).


Daeodon full body model at the Denver Museum of Nature and Science. Photo by the author, 2014. 

The relations of the entelodonts have been reflected on by many researchers, and in among the most recent additions to the literature, and the researchers involved found that the pig-like appearance of the entelodonts from which they get their popular nicknames (i.e., “terminator pig”) is rather misleading. Rather, the entelodonts seem to be more closely related to whales and hippopotami in a group termed the cetancodontamorpha (Spaulding, O’Leary & Gatesy, 2009).

In life, Daeodon leidyanum would have been a truly horrific sight as it hunted down fleeing mammals in the coastal forests of New Jersey. This ancient king of the forest was part of a great dynasty of carnivorous beasts which would only fall to extinction after many millions of years of success. Daeodon shows how wrong the belief is that extinction must mean some sort of evolutionary failure. Rather, the entelodonts were a success story, though like all species were unfit for some changing condition or conditions in their ecosystem, leaving only their devilish skulls and ancient skeletons behind for future creatures to observe.


Daeodon leidyanus by the author. Pencils on paper, 2016. 

For more on large mammalian predators of the eastern United States, see:

Antediluvian Beasts of the East: Pliocyon robustus


Marsh OC. 1893. Description of Miocene Mammalia. American Journal of Science 46(275): 407-412.

Gallagher WB. 1997. When Dinosaurs Roamed New Jersey. New Brunswick: Rutgers University Press. pp. 142.

Lucas SG, Emry RJ & Foss SE. 1998.Taxonomy and distribution of Daeodon, an Oligocene-Miocene entelodont (Mammalia: Artiodactyla) from North America. Proceedings of the Biological Society of Washington 111(2): 425-435.

Tedford RH & Hunter ME. 1984. Miocene marine-nonmarine correlations, Atlantic and Gulf Coastal Plains, North America. Paleogeography, Paleoclimatology, Paleoecology 47: 129-151.

Gallagher WB, Gilmore EJ, Parris DC, Grandstaff BS. 1995. Miocene mammals from the Kirkwood Formation of Monmouth County, N. J. In Baker JEB, ed: Contributions to the paleontology of New Jersey. Geological Association of New Jersey 12: 254-268.

Spaulding M, O’Leary MA & Gatesy J. 2009. Farke, AA ed. Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution. PLoS ONE 4(9): e7062. 





Antediluvian Beasts of the East: Carnufex carolinensis

A slight breeze blows the morning dew drops from the leaves of the plants surrounding the creek as a herd of herbivorous Coahomasuchus browse horsetails and ferns. These small armored reptiles are joined by a herd of large Gorgetosuchus, which bare magnificent spikes and ridges from their armored backs. These duck-billed armored herbivores or aetosaurs as they’re known are among the larger creatures to roam these forests, although they often fall prey to the many terrestrial and aquatic predators with which they coexist. 

Among such predators are phytosaurs, large, scaly hunters which bask along the banks of rivers waiting to snap at any passers-by. These cranky reptiles are hardly the devils of these forests , and often are frightened away by little but a scratch from one of the Gorgetosuchus’s shoulder spikes. Mobs of proterosuchids also line the water’s edge, but prefer fish and amphibians to the well-defended terrestrial herbivores. Often the aetosaurs must be more wary of the smaller but poisonous Uatchitodon, which scurry around in search of insects and small vertebrates to eat. When threatened, the small carnivores cower in a defensive posture. The small size of the Uatchitodon make them hard to spot, and often an aetosaur gains a scar from accidental confrontation with such small poisonous reptiles. 

Herds of large, cranky Placerias also pose a threat to the armored aetosaurs. The sparsely haired skulls of these cow-like herbivores bare large tusks that could easily cripple an ignorant aetosaur, and individuals from both Placerias and Gorgetosuchus herds bare evidence of confrontation with their large, herbivorous contemporaries. 

The aetosaurs’ greatest foe is an aged Carnufex bull. The old predator is a giant among the inhabitants of these woods, stretching 14 feet from nose to tail. He was once longer, but a chance encounter with a 3 meter subadult Carnufex caused the old bruiser to lose a small portion of the end of his tail. The old bull has a huge territory spanning almost six square miles, and has held the area for many years. The aetosaurs are easy prey for the aged reptile, who’s instinct gives away around the spiked herbivores’ armor. 

The aetosaurs, now finding themselves on a hill, start to chew through the vegetation covering the ground. Nearby is their silent enemy, the Carnufex bull, who hides behind a large boulder. The aetosaurs sense his presence, and as he appears from his bunker lower their bodies in defense. The gnarly scarred skin of the bull Carnufex gleams in the sun as he slowly creeps across the rocky soil in an austere manner, undaunted by the glimmering spikes of his targets. The bull suddenly erupts into a fury of predatory energy, latching onto the relatively unprotected head of one of the aetosaurs. His teeth sink into the aetosaurs face, blinding the poor herbivore. Disoriented, the herbivore stumbles while the other aetosaurs flee. The Carnufex bull now has the upper hand. Using his bodyweight, he pushes over the bloodied aetosaur, exposing its unprotected stomach. All the fleeing aetosaurs hear are the moans and growls of the combatants. Soon all falls silent, and another Triassic night sets in. 

Eastern North America has preserved an excellent record of the Late Triassic, with many formations bearing the remains of strange creatures of lineages long gone. Among those which contain the most complete record of this time is the Pekin Formation, which outcrops in the states of North Carolina. The Pekin Formation dates to approximately 231 million years ago, preserving some of the oldest known Triassic archosaur faunas in North America (Zanno et. al., 2015). Among the larger predators of this formation was Carnufex carolinensis, a relative of the ancestor of the group crocodylomorpha, which includes all modern day crocodylians and many other clades of extinct genera. Carnufex carolinensis would have been a large predator in life. The type specimen, a juvenile, would have already measured 3 meters long in life (Zanno et. al., 2015).

The most interesting thing about Carnufex carolinensis is not its size, but where as a predator it was in time. The Triassic provided an open door for evolution, as the Permian extinction had created unstable biological communities and altered ecosystems (Roopnarine et. al., 2007; Bambach, Bush & Erwin, 2007). New types of large predatory animals had room to grow.


The skeleton of Prestosuchus, a large Triassic pseudosuchian. Pseudosuchians were among the groups which gave rise to large predators during the Triassic. Photo by the author, 2015. Note the phytosaur skull in the background.

What Carnufex carolinensis shows is that crocodylomorphs were more diverse during the Triassic than previously thought, and alongside early dinosaurs were diversifying to become both apex and non-apex predators (Zanno et. al., 2015). Carnufex carolinensis itself is the largest known terrestrial predator known from the Pekin Formation, and was much larger than the earliest known North American theropods (Zanno et. al., 2015).

Within the Pekin Formation, Carnufex carolinensis would have coexisted with both a variety of predatory and a variety of herbivorous animals. Bulky dicynodonts would have lumbered around next to the armored aetosaurs Gorgetosuchus, Coahomasuchus, and Lucasuchus (Green et. al., 2005; Heckert et. al., 2015; Heckert, 2012). Predatory animals like cynodonts and phytosaurs also inhabited the formation (Liu & Sues, 2010; Baird, 1986).

Carnufex represents a group of archosaurs responding to new opportunities in a recovering ecosystem. However, the large, terrestrial crocodylomorphs of the Triassic were not to last. The End Triassic Extinction would see the replacement of such large bodied forms by theropod dinosaurs (Zanno et. al., 2015). Carnufex and its contemporaries in the Pekin Formation ecosystem represent a bouncing back from extinction, a rise from oblivion.

IMG_0005 (1)

Carnufex carolinensis by the author. Pencils on paper, 2016. 




  1. Zanno LE, Drymala S, Nesbitt SJ, Scheider VP. 2015.Early crocodylomorph increases top tier predator diversity during rise of dinosaurs. Scientific Reports 5: 9276.
  2. Roopnarine PD, Angielczyk KD, Wang SC, Hertog R. 2007. Trophic Network Models Explain Instability of Early Triassic Terrestrial Communities. Proceeding of the Royal Society of London B: Biological Sciences 274: 2077–2086.
  3. Bambach RK, Bush AM & Erwin DH. 2007. Autecology and the Filling of Ecospace: Key Metazoan Radiations. Palaeontology 50: 1–22.
  4. Green JL, Schneider VP, Schweitzer M, Clarke J. 2005. New evidence for non-Placerias Dicynodonts in the Late Triassic (Carnian-Norian) of North America. Journal of Vertebrate Paleontology Programs Abstracts 25: 65-66.
  5. Heckert AB, Schneider VP, Fraser NC, Webb RA. 2015. A New Aetosaur (Archosauria, Suchia) from the Upper Triassic Pekin Formation, Deep River Basin, North Carolina, U.S.A., and its Implications for Early Aetosaur Evolution. Journal of Vertebrate Paleontology 35: e881831.
  6. Heckert AB. 2012. Two New Aetosaurs (Reptilia: Archosauria) from the Upper Triassic Pekin Formation (Deep River Basin: Newark Supergroup) of North Carolina and the Phylogeny and Distribution of Aetosaurs. Geological Society of America Abstracts with Programs 44(7): 233.
  7. Liu J & Sues HD. 2010. Dentition and Tooth Replacement of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, U.S.A. Vertebrate Paleontology Asiatica 48: 169–184.
  8. Baird D. 1986. Some Upper Triassic Reptiles, Footprints and an Amphibian from New Jersey. The Mosasaur 3: 125-153.

Antediluvian Beasts of the East: Sauripterus taylori

Dust swirls through the water as a school of Bothriolepis fish hustle their way through the busy stream. Bothriolepis are the bullies of these waters, shoving off other fish using their bulky bodies and stabbing those which do not give them right of way with their sharp front fins. Bothriolepis are like tanks, the armored carapace which adorns the front of their body making the armored fish sink to the bottom of stream bed. 

These Bothriolepis belong to an ancient clade of fish called placoderms. Now, the group is extremely successful, but an extinction which soon shall exterminate a variety of creatures both flourishing in the seas and just colonizing land. Bothriolepis, though tyrannical in the way they treat the other fish of the stream, are little in this regard compared to their relatives in the open sea, wihch use giant body mouth plates to crush almost any prey animal they can find. Bothriolepis are also much more vulnerable than their cousins, as predators large enough to crush their protective armor still squeeze through the cramped waterways in which the placoderms live. 

The school of Bothriolepis swim through these busy waters for a purpose. Its breeding season for these fish, and both males and females are anxious to breed and escape back into the gloom of deep lagoons that jut into the land from the seemingly infinite greenish blue sea. The Bothriolepis are taking a risk, as their only predators in these waters prefer the large lakes where the armored fish go to breed. 

The school of armored fish arrives at their choice breeding spot. The Bothriolepis mate at the bottom of the lake, away from the watch of the wretched early tetrapods which line the banks to strike at sudden movement. These sluggish beats do well to wait on the banks, as they know bigger hunters occupy the water. 

On the side of the lake, ripples stirred by a the shadow in the water set the tetrapods galloping into the woods. The shadow, almost six feet long, is long and slender in shape. The figure does not yet spook the armored placoderms, who go on mating. Suddenly, a pair of Bothriolepis are sent flying out of the water, and the head of a massive fish bites off the unarmored abdomen and tail of the male fish, sending blood flying in all directions. The female, in shock, escapes the teeth of this monstrous predator. The hunter is a rhizodont, a type of large lobe-finned fish. The skin of this beastly fish is littered with scars, showing the age and stoicism of the predator. The rest of the Bothriolepis flee, but the giant rhizodont is still able to obtain two more meals. Once the armored fish are all gone, the rhizodont paddles back into the gloom of the lake, waiting for the memory of the attack to be forgotten and for new victims to enter its domain. 

Rhizodonts were giants among the Devonian fishes which pioneered the rivers and lakes of land. These fish are famous for their large size, with largest member of the group laying claim to the record of the largest known freshwater fish ever. However, some species included in the rhizodontida have evaded the interest of the public, including a species named Sauripterus taylori which swam through the lakes and rivers of the Northeastern United States over 300 million years ago.

Sauripterus taylori is known from a couple different specimens, all retrieved from the Catskill Formation of Pennsylvania. The Catskill Formation is a mostly terrestrial deposit, and was set down in the Late Devonian during a time known as the Famennian (Davis & Shubin, 2004). In the ecosystem the Catskill represents, Sauripterus would have swam alongside fish like the armored placoderm Bothriolepis (Stein, 2002). Along the shores of the lakes and rivers the rhizodonts inhabited, plants like Euphyllophytina would soak up sunlight (Stein, 2002). Remains of possible juvenile Sauripterus have also been unearthed from the famous Red Hill locality in Pennsylvania, where the large fishes would have coexisted with both tetrapods like Hynerpeton bassetti (Shubin, 2009) and the famously giant fish Hyneria lindae (Daeschler et. al., 2007).  

The fossils known of Sauripterus taylori provide key information on the structure of rhizodontid fins. The original specimen consisted of fragments of the animal’s head, scales, vertebrae, and a well-preserved right pectoral fin (Broom, 1913). More recently, another well-preserved right pectoral fin has been described (Davis & Shubin, 2004), suggesting that the pectoral fins of Sauripterus were well-adapted for propelling the large fish through the water and pushing the animal from the bottom of the lakes and rivers in which it inhabited. The limbs of Sauripterus would have allowed it to be both gigantic and powerful, enabling it to hunt both swift and slow-moving armored prey within the waterways of Devonian Pennsylvania.

Broom, 1913 suggested the original right pectoral fin specimen of Sauripterus taylori to be nearly identical to the ancestral tetrapod limb morphology. However, it has recently been found that the similarities of the limbs of early tetrapods and rhizodonts are a case of independently evolved traits (Davis & Shubin, 2004).

Sauripterus would have been an incredible predator in life. Its large size combined with its agility would have made the fish quite an imposing predator. Like in other rhizodonts, fangs and large tusks would have peeked from the front of the jaws of Sauripterus, sinking into the flesh of fish like fishing hooks. A powerful bite would have aided the large lobe-finned fish in attacking prey. Though we known little about this ancient predator, further excavations at sites like Red Hill may result in the discovery of better specimens, revealing a hunter long forgotten among the Devonian rocks of the Eastern United States.


Sauripterus taylori by the author. Pencils on paper, 2016.


Happy Earth Day! To read the last Antediluvian Beasts of the East installment, click the link below:

Antediluvian Beasts of the East: Dryptosaurus aquilunguis




  1. Davis MC & Shubin NI. 2004. A new specimen of Sauripterus taylori (Sarcopterygii; Osteichthyes) from the Famennian Catskill Formation of North America. Journal of Vertebrate Paleontology 24(1):26-40.
  2. Stein WE. 2002. SUNY-Binghamton Paleobiology Collection. URL: . Accessed April 13, 2016.
  3. Daeschler EB, Shubin NH .2007. New data on Hyneria lindae (Sarcopterygii, Tristichopteridae) from the Late Devonian of Pennsylvania, USA. Journal of Vertebrate Paleontology 27(S3): 65A.
  4. Shubin N. 2009. Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body. New York: Vintage. pp. 13. 
  5. Broom. 1913. On the Origin of the Cheiropterygium. Bulletin of the American Museum of Natural History 32: 459-464.


Antediluvian Beasts of the East: Dryptosaurus aquilunguis

Summer is the season which gives life to the animals of Cretaceous New Jersey. As the trees rustle in the cool breeze, a large bull Hadrosaurus minor grumbles to attract mates. His calls can be heard for miles, and can attract unwanted attention, including rival males. Hadrosaurus minor males frequently fight, sometimes killing one another in the heat of battle. Luckily for this male, only females appear from the forest, made interested by the hadrosaur’s distinctive bellows. The females will graze in close proximity to the male until they are ready to mate. However, this time of plenty will soon end, giving way to the cold, wet months of winter.

The vast expanses of the New Egypt wilderness host more then just dinosaurs. Crocodilians and marine reptiles frequent the area during the warm summer, feasting on the schools of fish which shoot up the deltaic plains of the coastal lowlands. Among them is the 14 foot long Thoracosaurus, a long-snouted crocodilian specializing in fish-hunting. These slender predators follow the large schools of Enchodus fish up and down the eastern shoreline of Appalachia. In winter, the cold-blooded thoracosaurs will leave the deltas of the Navesink for warmer hunting sites elsewhere. Other predators of the deltas, such as the mosasaur Halisaurus, will eek out a living a few miles off the coast of Appalachia, where they will be exposed to larger predators.

For other animals of the New Egypt wilderness, the coming winter months pose more of a threat. Many of the large herbivorous dinosaurs of the region will be forced into the nearby Appalachian mountains, which in the west eclipse their summer home of plenty. To reach the plateau within the mountains, the large herbivores of the region must embark on a long trek across 50 or more miles of treacherous terrain, and many will not survive.

Fall, and the calls of another large animal fill the New Egypt wilderness. Lambeosaurines, some 26 feet in length, are forming gigantic migrating herds. Males of this dinosaur are adorned will colorful head crests which they use to deter rivals and predators. The already forming heavy proto-feather coats of these hadrosaurs signal the coming of winter. They must store up fat to survive to cold, or else they will never see spring. Juveniles are especially at risk, and often will not even survive the first days of the trek up the mountains.

For another type of animal, the coming of winter is an advantage. The top predators of the region have been busy all summer raising the next generation, but now they stir from their nests. The most common species here is Dryptosaurus aquilunguis. Packs of these killers will torment the herds of herbivorous dinosaurs making their way through mountain passes. Unlike the hadrosaurs, whose bristly and somewhat sparse coats provide only a little protection from the cold, Dryptosaurus aquilunguis sport a coat of feathers similar in structure to the downy feathers of birds. Their warm coat provides a huge advantage when cold weather sets in, allowing them to thrive in the cold winter. Their padded feet, armed at the tip with large claws, give them ample traction during their climb up the sometimes rocky faces of the Appalachian mountains.

Winter finally shows its ugly head to the animals of the Appalachian wilderness. Although there will be little or no snow, long-lasting storms will drench the deltas with ice-cold water and temperatures will drop to an average of 2 degrees Celsius. The small animals of the deltas, like salamanders and frogs, will cling on to life here as best they can, but the large animals will now have to leave. The hadrosaurs start to march up the mountains, and are followed by the hungry Dryptosaurus aquilunguis, which seek to prey on the duck-billed dinosaurs. These predators hunt and kill dozens of hadrosaurs during the start of winter, feasting on the remains of the weary herbivores. Winter, however, will even test the might of the dryptosaurs, as the worst is yet to come.

Mid-December, and the battalions of migrating dinosaurs find themselves among the cold forests of the plateau they’ve set on out for. Even in these forests, insulated by mountains all around them, the height of winter is desolate, and sleet, hail, and rain are common sights. For the groups of dryptosaurs, these are the days which put them to the test. Among the trees, a mating pair cuddles for warmth. The hadrosaurs are faring even worse then their predators, and many browse among the bodies of their brethren which have succumbed to the cold. The hadrosaurs would fare even worse back in the coastal lowlands, where the constant cold weather kills the plants of the deltas. The pine trees here barely sustain these majestic titans, which, in turn, allow the dryptosaurs to survive.

As the hadrosaurs browse, the mating pair of dryptosaurs find a native resident of these alpine woodlands. A nodosaur, decked in armor from nose to tail, rips bark off the sleet-covered conifers as the theropods watch from behind a grove of dead magnolia trees. The female dryptosaur cautiously approaches the armored herbivore, which grunts to deter her. Taking notice, the dryptosaur backs off, deciding not to mess with an unknown herbivore. The Dryptosaurus aquilunguis will have to settle for hadrosaur meat.

Late January, and signs of spring bring hope to the weary dinosaurs. The dryptosaur pair has survived, and have been tracking a small group of ornithomimosaurs for a few days. They finally strike, killing a large ornithomimosaur using their immense hand claws. These weapons are only found on dryptosaurs, giving them another advantage over the other lineages of large predator that live in the Navesink ecosystem. These theropods have braved the harsh Appalachian winter, and are rewarded by warmer weather.

This same rise in temperature signals the herds of hadrosaurs to migrate back to the lowlands, where they will be joined by groups of leptoceratopsids which have migrated back to their summer home from the south. The hadrosaurs seem joyful as they march through the same mountain passes they faced months earlier.

As the herds of dinosaurs march back, the fading winter lashes out once more. A sudden downpour of sleet and snow rivets the migrating animals, who have already lost some of their winter coats. The storm has come from the cold, high peaks of the northern Appalachians, where winter always lurks. The hadrosaurs, however, will survive, due to the pounds of conifer matter they ingested while staying in the high plateau. The dryptosaur pair escape the storm undaunted, feeding on the carcass of a dead pterosaur which fell from the skies during one of the harsh storms of mid-winter.

The hadrosaurs have finally reached the promised land. They have braved the harsh wintry months, and feast on the warm, succulent plants of the deltas. For the dryptosaur pair, the end of winter gives way to another event. The spring is the mating season of the dryptosaurs, and the female Dryptosaurus aquilunguis of the pair will soon lay a clutch of eggs. By the middle of summer, the dryptosaur pair will welcome chicks. When again the onset of fall signals the migration of the hadrosaurs, these chicks, alongside their parents, will face the sleet storms of deep winter, and, if they survive, will join their parents in being the most versatile predators of the Cretaceous.

Dryptosaurus aquilunguis remains one of the most important dinosaurs in the history of paleontology. The remains of this large predator, discovered during the late 1800s, would set the foundation for the concept that dinosaurs were extremely active, adaptable animals, contrasting with the view of them as lumbering “evolutionary failures”. To completely understand the role Dryptosaurus aquilunguis played in what would eventually be known as the Dinosaur Renaissance, we must first venture to the time when the D. aquilunguis type specimen was discovered and uncovered from a marl deposit in Barnsboro, New Jersey.

It’s the late 1800s, and the partial skeleton of a predatory dinosaur is removed from New Jersey sediment. The excavation is under the watch of Edward Drinker Cope, a young paleontologist and comparative anatomist living in Haddonfield, NJ (Gallagher, 1997).  Incredibly, the theropod specimen is more well-preserved than any other found before it, provoking much excitement among Edward Cope and his team. Cope envisioned this new killer as an active hunter, running and leaping across the ancient New Jersey environment. Cope named the animal Laelaps aquilunguis, the “eagle-clawed catcher of all its quarry”, alluding to the dog Laelaps, which, in Greek mythology, always caught whatever it pursued. The success of the discovery of Laelaps prompted Cope to continue his excavation and exploration of the animals of the New Jersey marl, and more fascinating discoveries followed.

Cope had won the lottery. He knew Laelaps was related to the European Megalosaurus (another predatory dinosaur only known from scrappy remains) and since the former was known from a specimen far more complete then the latter, Cope could continue his mentor’s (influential paleontologist Joseph Leidy) work in finding out what these ancient creatures actually looked like in life. Cope’s Laelaps started to make scientists wonder if dinosaurs were active animals rather then the slow moving-behemoths they had been thought to be previously. It turned out Cope was correct in thinking that dinosaurs were very active animals, and the legacy of his “leaping Laelaps lives on today.

All this excitement attracted another prominent young scientist by the name of Othniel Charles Marsh. Marsh and Cope had known each other previously, but now Marsh had a more devious agenda. Marsh wanted some of the New Jersey marl specimens for himself, and during his stay started to establish his own group of marl diggers (Gallagher, 1997). Marsh and his newly-found henchmen started to collect the best specimens from the marl, much to Cope’s suspicion. Marsh also took it upon himself to publicly humiliate Cope any chance he got to,with  one of the most famous incidents concerning the plesiosaur Elasmosaurus. Marsh even took away Cope’s prize animal: Laelaps. Pointing out that the genus name in question  was already given to an arthropod, Marsh re-described Cope’s pride and joy as Dryptosaurus aquilunguis, the “eagle-clawed tearing lizard” (Gallagher, 1997), a name which still stands today. Cope was devastated, and continued to use Laelaps in his papers to refer to carnivorous dinosaurs (Gallagher, 1997). In his later years, Cope  would work with the artist Charles Knight to create a restoration of two Dryptosaurus fighting each other, a piece of paleoart which still sets the standard for paleontological illustration. 

Although Cope’s Laelaps might not have lasted, his theories on the ecology of the dinosaur did. Future discoveries would paint a dynamic picture of dinosaurs as active animals, asserting that his vision of Dryptosaurus as an active animal was true. Today, Dryptosaurus and its relatives (tyrannosauroids) are known to be fast, powerful predators just as Cope had envisioned. However, today the remains of Dryptosaurus are little compared to the material we have of other dinosaurs, and so some deduction and guesswork is required to understand the species ecologically, anatomically, etc.

The holotype of Dryptosaurus aquilunguis was unearthed from the New Egypt Formation (Brusatte et. al., 2011), a Maastrichtian-age (~72-65 MYA) deposit in what would become New Jersey. The New Egypt Formation is especially important as it provides a glimpse into one of the last Mesozoic Appalachian ecosystems. In fact, just above the New Egypt lies the Hornerstown Formation, a deposit which records the faunal change from a latest Cretaceous ecosystem including animals such as Mosasaurus sp. to a Cenozoic ecosystem recovering from the K-T extinction event. However, the Hornerstown does not contain the diverse dinosaurian fauna present in the New Egypt. Within the latter formation, Dryptosaurus aquilunguis had access to a wide range of dinosaur prey, including Hadrosaurus minor, another unnamed “duck-billed” dinosaur genus, and lambeosaurine hadrosaurs. Furthermore, ornithomimosaurs of the taxon Coelosaurus antiquus were also present within the New Egypt ecosystem, providing another food source for the aptly-named “tearing lizard”.

Although many of the dinosaurs and other animals present in the ecosystem of Dryptosaurus aquilunguis were related to forms in western North America and Asia, the morphology of these Appalachian forms differed from their relatives which lived far away. This is likely due to the unique faunal interchange which had defined the fauna of Appalachia ever since its start during the Cenomanian. Before the breakup of the North American landmass during the Late Cretaceous, an almost homogenous fauna could be found across the continent. On the east coast, the presence of a dinosaurian fauna almost completely homogenous to that of the west (Deinonychus sp., Tenontosaurus sp. , titanosauriformes, nodosauridae, allosauroidea) is found within the Arundel Formation of Maryland (Weishampel, 2006). Surprisingly, the Arundel Formation also shows the beginnings of changes in the North American fauna. The remains of an indeterminate ornithomimosaur and more surprisingly a tooth assigned to an indeterminate neoceratopsian have also been unearthed (Weishampel, 2006).


Deinonychus, a likely component of both eastern and western North American dinosaurian fauna. Photo by the author, 2015.

Skip ahead a couple million years, and Cenomanian Appalachia bears a “chimaera fauna”: a mix between taxa belonging to groups which had lived across the continent before the breakup of Laramidia and Appalachia and taxa which had evolved on or migrated to Appalachia. The best record of this time on Appalachia comes from Texas, where the Cenomanian Woodbine Formation preserves the remains of both animals with relatives found in the Arundel (nodosauridae, allosauroidea, dromaeosauridae) (Main, 2013)(Lee, 1997), but also those which do not have close relatives within the earlier formation (Protohadros) (i. e. Main, 2013). However, Protohadros does seem to have close relatives in the west (Prieto-Marquez & Norell, 2010)(Wenhao & Godefroit, 2012), suggesting that faunal interchange between Laramidian and Appalachian animals did occur at least in one direction.

Travel to the Campanian, and Alabama preserves a dinosaurian fauna seemingly created by the mixing of endemic and foreign fauna. Here, a derived non-tyrannosaurid tyrannosauroid (Appalachiosaurus) and a close relatives of hadrosaurids (Lophorhothon) appear, albeit not in the same formation. Finally, the Maastrichtian and Campanian sediments of New Jersey, North and South Carolina, Delaware, and Missouri preserve a terrestrial fauna almost completely unique from one anywhere else on the globe. Giant primitive hadrosaurids (Hypsibema, Ornithotarsus, “Parrosaurus”) are found across the continent, along with oddly primitive hadrosauroids (Lophorhothon, ?Claosaurus), hadrosaurines, which varied greatly in size (Hadrosaurus foulkii, Hadrosaurus minor), and leptoceratopsids (Longrich, 2016). 


Hadrosaurus foulkii fossils displayed at the Philadelphia Academy of Natural Sciences, Drexel University. Photo from Wikipedia.

Along with these animals, which seemingly arose on Appalachia after the splitting of the North American continent, forms found on eastern North America during the Early Cretaceous days of the Arundel Formation are still found within the ecosystems of Appalachia. Ornithomimids and nodosaurs are present in New Jersey, the Carolinas, and Alabama. Dromaeosaurs are also present in Alabama and possibly the Carolinas and New Jersey. Finally, primitive tyrannosaurs (Dryptosaurus macropus, Dryptosaurus aquilunguis, Appalachiosaurus montgomeriensis), echoes from the Early Cretaceous when their kind were just starting to become large predators, are the big-game hunters of Appalachia. The presences of a distinct fauna on Appalachia is supported by Longrich (2016).

The distinct fauna of Appalachia might also explain the intriguing morphology of some of material we have of Dryptosaurus aquilunguis. The massive hands tipped with huge claws which the “tearing lizard” possessed point to the prospect of this Appalachian tyrannosauroid employing a different style of attack than that of its western counterparts. Brusatte et. al. (2011) pointed out that the forelimb morphology of D. aquilunguis was “unlike that of any other tyrannosauroids”. The 2011 study also concluded Dryptosaurus had lost some grasping ability in comparison with more basal tyrannosaurs. Furthermore, unlike the tyrannosaurids of the west which possessed large, robust skulls (i.e. Tyrannosaurus, Daspletosaurus), Dryptosaurus seems to have possessed a more delicately constructed skull and, also unlike western tyrannosaurs, ziphodont teeth (Brusatte et. al., 2011).

Clearly Dryptosaurus was employing a different hunting style than other large tyrant dinosaurs, and the reason for this was perhaps due to the different types of prey the tyrannosaurs of the east and west were hunting. These features are, however, similar to those found in allosauroids, which are sometimes thought of as hunters of large game such as sauropods and non-hadrosaur ornithopods. The hadrosaurs of the east coast can be thought of as analogous to these other herbivorous dinosaur groups as they did possess large size in many cases and also seem to have not possessed any obvious defensive features (spikes, horns, armor).


The skeleton of Tyrannosaurus rex, a tyrannosaurid tyrannosauroid showing the robust skull morphology and small arms associated with derived tyrannosaurs. Photo by the author, 2015.

Almost the exact opposite occurs in many groups of large herbivores in the west, where ceratopsids boasted a menagerie of different horns and frills, ankylosaurs were coated in a tough layer of bony scutes and plates, and pachycephalosaurs sported domed, spiky heads. The tyrannosaurids of the west lived in a land where the “plain” hadrosaurs were in well-armed company. Dryptosaurus seems to have lived in an ecosystem where large animals with obviously defensive features were less common (a leptoceratopsid is known from the Tar Heel Formation of the Carolinas (Longrich, 2016), and nodosaurid material from the Campanian and Maastrichtian New Jersey has also been recovered (Weishampel, 2006), and that’s pretty much it as far as Appalachian dinosaur with defensive capabilities go). Dryptosaurus likely would have hunted and killed hadrosaurs by slicing flesh with its teeth and large claws, thereby inducing blood loss.

Dryptosaurus aquilunguis remains one of the most astounding dinosaurs ever found. The incredible history of its collection combined with its peculiar anatomical features stand as a hallmark of paleontological discovery in eastern North America as well as in the rest of the word. The “tearing lizard” truly is an amazing dinosaur, a hallmark of the fantastic animal oddities which evolved on the forgotten continent of Appalachia.



Dryptosaurus aquilunguis rests within the coastal forest that will one day become the New Egypt Formation. Also pictured are the ornithomimosaur Coelosaurus antiquus, an unnamed lambeosaurine hadrosaur, a dromaeosaurid, and enantiornithine birds. Foliage includes Metasequoia sp. (Dawn Redwood), Liriodendron (Tulip Trees, leaves pictured), Picea sp. (Spruce Tree), rosaceae sp., and Humulus sp. Illustration by the author. Colored pencils on paper, 2016.

For more on the dinosaurs of Cretaceous Appalachia, see these articles:

Antediluvian Beasts of the East: Hypsibema crassicauda

Antediluvian Beasts of the East: Hypsibema missouriense

Antediluvian Beasts of the East: Ornithotarsus immanis

PaleoNews #18 (National Fossil Day 2015 Special Edition) 


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