Preprint Published: Ornithomimosaurs from the Arundel Formation

Hi everyone! I’ve been researching for a bunch of manuscripts all this past spring. Check out this new preprint on the ornithomimosaur materials from the Arundel Formation:

https://peerj.com/preprints/2308/

Additionally, I regard the Utah taxon Nedcolbertia justinhofmanni as an intermediate non-ornithomimid/deinocheirid ornithomimosaur. It shares a single flexor fossa on its pedal unguals and anteroposteriorly short phalanges from pedal digit IV with ornithomimosaurs (Brownstein, 2016) (listed as synapomorphies of the group by Choiniere, Foster & De Klerk (2012)). It also has metatarsals more elongate in form than tyrannosaurs and a proximally pinched metatarsal III.

What’s interesting to me is that the shape of metatarsal III of the Arundel form suggests that it had a more derived metatarsus condition than Nedcolbertia. I use this and a temporal comparison of the formations in which Nedcolbertia, the Arundel taxon, and what I believe to be its close relative (Kinnareemimus) to support my theory that ornithomimosaurs with different metatarsus conditions coexisted in North America (Brownstein, 2016). Unfortunately, the paucity of decent North American ornithomimosaur material from the Early Cretaceous of North America makes any analysis of possible ecological interactions between ornithomimosaur lineages ill-informed (Brownstein, 2016). It is interesting to note, however, that Nedcolbertia can be differentiated by many ornithomimosaurs by its manal morphology and simplistic and pneumatic dorsal vertebra (Kirkland et al., 1998).

All in all, the Arundel dinosaur fauna is in serious need of more research. If there’s any dinosaur researcher out there looking for something to study, the Early Cretaceous dinosaurs of Maryland are just another opportunity to be found in the eastern United States and Canada.

EDIT: Just fixed some reference formats and added a figure showing the metatarsals. Oh well. New version will be out soon.

References.

  1. Brownstein CD. 2016. Redescription of Arundel formation Ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an “Ostrich Dinosaur”: Biogeographic implications. PeerJ Preprints 4:e2308v1. 
  2. Choiniere JN, Forster CA & De Klerk WJ. 2012. New information on Nqwebasaurus thwazi, a coelurosaurian theropod from the Early Cretaceous Kirkwood Formation in South Africa. Journal of African Earth Sciences 71–72: 1–17.

  3. Kirkland JI, Whittle CH, Britt BB, Madsen S, Burge D. 1998. A Small Theropod from the Basal Cedar Mountain Formation (Lower Cretaceous, Barremian) of Eastern Utah. In Lucas SG, Kirkland JI & Estep JW, eds:Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin 14: 239-248.

Antediluvian Beasts of the East: Daeodon leidyanus

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.

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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).

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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.

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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

References.

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

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.

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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.

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

 

 

References 

  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

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.

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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

 

 

References

  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: fossilworks.org/bridge.pl?a=collectionSearch&collection_no=28211 . 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: Errimonykus colayae

Antediluvian Beasts of the East: Errimonykus colayae

The ice forms brittle plates as it encapsulates the cold, dark sea. Whale-sized mosasaurs swim beneath the ice, their lizard-like scales gleaming in the beams of sun which pierce through the crusty surface of the water. This is no place for the light of heart. Only the toughest of dinosaurs live here, including herds of battle-worn hadrosaurs which nibble at the ice for water, heading back to the shore to eat low-lying shrubs. 

Other, more ferocious dinosaurs live here. Amongst them are the tyrannosauroids, which use their large hands and claws to swipe and and impale their victims. The tyrannosauroids vex the hadrosaur herds, the frequent appearance of their sleek feathered coats in the mist above the ocean making the beaked herbivores nervous. The tyrannosaurs, however, are not the hadrosaurs main worries. Rather, their anxiety comes from other, smaller predators. 

One such hadrosaur has the misfortune of being at constant war with these small hunters. He is a large bull, and at 12 meters, he has little to worry about from the tyrannosaurs. However, he must live in constant pain from the attacks of Erimmonykus colayae. These small predators gnaw at the hadrosaur’s tough hide, constantly biting and tasting the herbivore’s flesh. Biting and gnawing and biting and gnawing seem to be the constant actions of the dromaeosaurs. The predators’ teeth have grown blunt from their use, and will soon be replaced by new sets of fangs. In the meantime, the bluntness of the dromaeosaurs’ teeth makes life for the hadrosaur even more miserable, as the fangs cause bruising and are a constant itch. This hadrosaur is particularly unfortunate, as five of the dromaeosaurs have latched on to his flesh for around a year. Erimmonykus attack the hadrosaur in a very sadistic way, waiting for the wounds they’ve inflicted on the poor dinosaur to heal before once again feeding on the flesh of the herbivore. The bull hadrosaur will also have to cope with the burden of the dromaeosaurs’ weight, which increases greatly the longer he carries them with him. He may find salvation if the dromaeosaurs find better-tasting meat, but Erimmonykus rarely leave their victims. Such is life in these harsh lands. 

Erimmonykus colayae was a dromaeosaurid, or “raptor” dinosaur of the subfamily pseudolovecrafinae recently described by Outis, Nemo, Nein & Young (2016) in the journal Introspective Advances in Theropods. Like other pseudolovecrafinines, the skull of E. colayae was robust and elongated. The sharp, serrated teeth of this animal formed 20-degree angles with the animal’s upper jaw, while the bottom teeth were isosceles and serrated on both sides. Large eyes would have been present in the animal, likely for spotting prey in the dark. Finally, a short body and large tail would have given the animal a bird-like appearance.

The most incredible adaptation of E. colayae was its odd foot morphology. Unlike other dromaeosaurs, the claws of E. colayae bore large areas of muscle attachment, seemingly to grasp on to objects for an extended amount of time. However, the lower leg of E. colayae is simplified, bearing resemblance to that of an ostrich. This morphology suggest that E. colayae did not use its highly adapted claws to navigate trees, but rather to cling on to the ground or perhaps more likely into prey items.

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The claw of Errimonykus colayae.

 

Parasitism as a possible lifestyle for dromaeosaurs has previously been discussed in scientific literature (Fraser, 2014). In fact, this lifestyle has also been discussed to be the reason why dinosaurs like Triceratops and Stegosaurus evolved frills and bony plates. These structures would have protected the herbivores from being latched onto by dromaeosaurs. However, E. colayae seems to have taken this lifestyle even further, as it seems to have been able to latch onto prey for long periods of time. E. colayae comes from the far north  of the continent Appalachia in an area dubbed “Errim” by Outis, Nemo, Nein & Young (2016). The locality from which the holotype of E. colayae was discovered also bore the remains of basal hadrosaurid dinosaurs. As hadrosaurs did not evolve any structures like the plates of Stegosaurus on their back, they would have been the perfect targets for E. colayae to latch onto. The claws of E. colayae would have slashed into the skin of these herbivores, their serrated undersides catching on the flesh of the poor hadrosaurs. The dromaeosaurs would nibble on the exposed tissue of the animal. The pain must have been excruciating.

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E. colayae by the author. Pencils on paper, 2016.

Unfortunately for E. colayae, the Late Cretaceous would soon draw to a close. The meteorite that would slam into the Yucatan Peninsula would also send large waves crashing through the seas surrounding Appalachia. With it, the Errim ecosystem would be destroyed. No longer would E. colayae irritate herbivores for long amounts of time. The most sadistic predator in Earth’s history would go extinct.

References 

Outis NG, Nemo FI, Nein BS, Young NY. 2016. A new dromaeosaurid coelurosaur theropod  from a new geographic area pertaining to the continent Appalachia and its implications for dromaeosaur parasitism. Introspective Advances in Theropods 1295: 332-560.

Fraser G. 2014. “Bizarre Structures” Point to Dromaeosaurs as Parasites and a New
Theory for the Origin of Avian Flight. The Journal of Paleontological Sciences 1: 1-27.

Scans, glorious scans

Hi everyone. I’ve been working on the book and research has led me to Donald Baird’s 1989 paper “Medial Cretaceous carnivorous dinosaur and footprints from New Jersey” which was published in the journal Mosasaur. If anyone has a scan of the paper or of the figures of the footprints included within the paper, it would be really helpful if you could share them with me. Thanks!

References 

Baird, D. 1989. “Medial Cretaceous carnivorous dinosaur and footprints from New Jersey.” Mosasaur 4: 53-63.