Antediluvian Beasts of the East Season 1 : The Extraordinary and the Elephantine

Antediluvian Beasts of the East : Pliocyon robustus

The grass whistles in the wind as sea-spray is blown from the nearby Atlantic Ocean. This is Florida, but not the one we know today. It is the Miocene, and in the place of wetlands and palm trees are plains and small forests. These wide expanses of grassland are home to a variety of fauna, some just as seemingly alien as the biomes they live in. Among the more recognizable fauna is horse Astrohippus, a close relative of modern zebras and Przewalski’s horses. Astrohippus travel in large herds, up to 100,000 strong, which continuously roam the plains in search for fresh food. Males of this species have large, black manes which they use in territorial displays and courting rituals. Astrohippus are also very aggressive, and often kill or injure themselves in disputes.

Neohipparion and Hypohippus are also found on the plains in small herds, and browse on a variety of plants. These horses are most at home in the small groves which dot the grassland. Their hides, a mixmatch of grey, black, and white patches, camouflage the horses among the trees and bushes. Although not as aggressive as the Astrohippus, these horses will kick if threatened, and often an unlucky predator is killed in a dispute with a Hypohippus. Small herds of these horses will join the Astrohippus during the wet season as they migrate to coastal wetlands.

One of the weirder residents of the grasslands is the rhinoceros Teleoceras. These barrel-bodied grazers are armed with plate-like folds of skin that act as body armor, and a small nose horn. Their heavy size also poses a challenge to predators. Teleoceras also join the horses during the wet season, but are the most uncommon animals in the herds.

Evening, and a mixed herd of horses and rhinoceros stop at a waterhole surrounded by forest, intent on spending the night in the seemingly peaceful setting. Yet the herd is not so lucky as to have a peaceful evening. Suddenly, as if they were ghouls manifesting in the night, a dozen or more Borophagus, the aptly nicknamed “bonecrushing dogs”, emerge from the forest. The horses and rhinoceroses are thrown into a panic, and some flee into the water. The Borophagus start to harass the herd, picking off any animal they can get their teeth around. The Teleoceras are having none of it and run for the hills, flinging any bonecrushing dogs out of their way using nose horns. Unfortunately for the herd animals still caught in the ordeal, it’s about to get much worse.

Alerted by the commotion, marine predators flock to the violent scene. Among these are Alligators of the genus Alligator, which drag unlucky horses down into the muddy water. On land, several Epicyon, larger relatives of Borophagus, join the bloodbath, ripping flesh ad breaking bones. A few of the fox-like Vulpes stenognathus are attracted to the scene, and dodge the larger predators for their chance at a meal. Even worse for the horses, the largest predators of these lands have yet to arrive.

A few hours have passed, and the mass-predation event continues full-fledged. The Epicyon have dragged a couple carcasses away, and have left the scene altogether. The Borophagus, Alligator, and Vulpes stenognathus are joined by a large bear of the genus Agriotherium, who has already taken out a large male Hypohippus. 

As the predators enjoy the fruits of their labor, a roar, sounding like a mix between that of a wolf’s snarl and a bear’s growl, is heard from the forest. Just as the predators perk up their heads to see the sound’s origin, two streamlined forms jump from the thicket. These are Pliocyon robustus, the apex predator of these plains. The Borophagus, watching the two bear-dogs charge, anxiously wait the fight to come. As soon as they reach the herd, the two bear-dogs, each weighing around 450 pounds, start to take on a large male Astrohippus. One of the Pliocyon robustus jumps on the horse, holding the herbivore in place, while the other bear-dog severs the horse’s trachea with a bite to the neck. As one of the Pliocyon robustus digs into the fresh kill, the other charges toward a group of Borophagus feeding on the carcass of a Hypohippus. The bear-dog, growling at the bonecrushing dogs, leaps up on the carcass and lunges at the smaller predators. One Borophagus jumps for the bear-dog in a counterattack, but is knocked to the ground with a swipe of the female Pliocyon robustus’s arm. The other Borophagus, appalled at the sight of their comrade’s undoing, grab what horse meat they can and sprint away. At the sight of their departure, the female bear-dog gorges herself on the remaining carcass.

The Agriotherium, noticing the dispute between the Pliocyon robustus and the Borophagus pugnator, starts to growl at the bear-dogs, who roar back in retaliation. The bear, angered by the bear-dogs’ reaction, starts to charge, and is met by both bear-dogs near a carcass of a small Neohipparion. The bear rears up to a height of 10 feet as he tries to scare the bear-dogs. Undaunted, the Pliocyon fight back, and one scratches the nose of the bear, causing the Agriotherium severe pain. The bear does, however, manage to hit the male the bear-dog in the arm, leaving three small gashes which will, in time, scar. Enraged, the Pliocyon robustus slashes the thigh of the bear. The bear, bruised and beaten, growls and limps away. The bear will survive, but the encounter will leave a large, visible, discolored scar on the bear’s right leg.

Morning, and the sun sheds light on the outcome of the mass-predation event. The herd has moved on, leaving several carcasses on the shores of the waterhole, with many more dragged into the lake by Alligators. The Pliocyon robustus, who’ve continued to eaten throughout the night, rest under a small tree as a few Alligators bask in the sun behind them. Several hours later, the Pliocyon robustus wake from their slumber and run off. An hour later, they arrive at a small thicket, and are greeted by four small faces peeking out of the bushes. These Pliocyon robustus are a mating pair, and will raise their young to become the some of the most fearsome predators in Miocene North America.

Pliocyon robustus is a large amphicyonid (more commonly known as a “bear-dog”) from the Bone Valley Formation of Florida (Berta & Galiano, 1984). This large species of bear-dog is known from a mandibular ramus dating to the Clarendonian North American faunal stage of the Miocene epoch (Berta & Galiano, 1984).

Left mandibular ramus of Pliocyon robustus. From Berta & Galiano (1984).

Left mandibular ramus of Pliocyon robustus. From Berta & Galiano (1984).

As seen in the image above, the mandibular ramus of Pliocyon robustus is short in proportion compared to other amphicyonids, and also larger and more robust then that of Pliocyon medius (Berta & Galiano, 1984). So how big was this amphicyonid, exactly? The length of the mandibular ramus of Pliocyon robustus is around 87.3% of the length of the ~28.5 inch long SDSM 571, the left mandibular ramus of an Ischyrocyon gidleyi (See this post by the Museum of Geology for more on SDSM 571). SDSM 571 is from  Mission Pit, South Dakota, which is generally thought to be of Clarendonian age (Famoso & Pagnac, 2011). Therefore, I will use the mass estimate Figueirido et. al. (2011) found for Ischyrocyon individuals of Clarendonian age to estimate the mass of Pliocyon robustus. We multiply 546 kg (Figueirido et. al.’s mass estimate for Clarendonian Ischyrocyon) by 87.3/100 and voila, we get 476.658 kilograms, or 1050.85 pounds.

Of course, the mass estimate I found is tentative and was only calculated to give the reader an idea of the mass of Pliocyon robustus. That being said, the mass estimate just calculated shows that Pliocyon is among the largest amphicyonids, only beaten by Amphicyon ingens at 579 kilograms, Pseudocyon sp. from New Mexico at  773 kilograms, and Claredonian Ischyrocyon gidleyi at 546 kilograms (Figueirido et. al., 2011). If Pliocyon robustus was overall as robust as its left mandibular ramus is in comparison to other amphicyonids, Pliocyon robustus may have approached the masses of the largest amphicyonids.

The amphicyonids themselves were a diverse race of macropredatory carnivorans which existed for around 10 million years. They were extremely successful, and spread all over the world from North America to Asia. These killers were the top predators of their time, preying on the variety of herbivorous mammals present in the Miocene and Pliocene.

Amphicyon ingens, a relative of Pliocyon robustus. Photo by the author, 2015.

Amphicyon ingens, a relative of Pliocyon robustus. Photo by the author, 2015.

In fact, remains of the horses Astrohippus martini and Hypohippus chico are known from the same site that the holotype of Pliocyon robustus was recovered from (Berta & Galiano, 1984). It is probable that the large amhpicyonid preyed on these horses, chasing them down in the grasslands of the Miocene.The environment of Pliocyon robustus would have been similar to these plains. Photo by the author, 2015.

The environment of Pliocyon robustus would have been similar to these plains. Photo by the author, 2015.

The rule of the amphicyonids, however, was not to last. With time, they decreased in numbers, dwindling to extinction during the Pliocene. Perhaps the newly evolved forms of large felines and pack-hunting canids outcompeted the amphicyonids. Maybe the amphicyonids couldn’t cope with the newly evolved fast-moving fauna which replaced the slow, sometimes bulky mammals they so relied on for food. Whatever the reason, the amphicyonids became extinct. Out of them, Pliocyon robustus, the once-fearsome king of the Florida plains, would be remembered by the lower jaw of a single animal, bearing the killing canines of one of the most successful lineages of predatory mammals to have ever existed.

References

1. Berta, A.; Galiano, H. .1984. “A Miocene Amphicyonid (Mammalia: Carnivora) from the Bone Valley Formation of Florida.” Journal of Vertebrate Paleontology 4(1): 122-125.

2. Famoso, N. A.; Pagnac, D. .2011. “A Comparison of the Clarendonian Equid Assemblages from the Mission Pit, South Dakota and Ashfall Fossil Beds, Nebraska.” Transactions of the Nebraska Academy of Sciences and Affiliated Societies 32: 98-107.

3. Figueirido, B.; Pérez−Claros, J. A.; Hunt, R. M. Jr.; Palmqvist, P. .2011. “Body mass estimation in amphicyonid carnivoran mammals: A multiple regression approach from the skull and skeleton.” Acta Palaeontologica Polonica 56 (2): 225–246.

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Antediluvian Beasts of the East : Ornithotarsus immanis

It’s morning in the woodland, 79 million years ago, and the sounds of the forest greet the rising sun. Within a cluster of Gunnera plants, a male dromaeosaurid displays his plumage to a somewhat uninterested female, while a pair of mammals dash across the earth. A sudden, triumphant bellow sends the dromaeosaurids darting into the trees, leaving the mammals to forage in peace. The bellow came from a young male Hadrosaurus foulkii, the most common dinosaur of the woodland. Typically, Hadrosaurus foulkii travel in closely-knit herds, but males are often exiled, only to return to the herd during mating season. Being solitary means that this young male Hadrosaurus foulkii lacks the protection of the herd, and is an easy kill for the predators of the forest. Yet predators aren’t the only threats in these woods.

The young male hadrosaur stops to browse on some tall shrubs, without a whim in his mind, but suddenly, with the volume of a ship horn, an immense bellow from behind the shrubs makes the young hadrosaur jump. The emperor of these forests has arrived. Meet Ornithotarsus immanis. This 39 foot, 7 ton male is twice as long and three times as heavy as the 20 foot, 2 ton young male Hadrosaurus foulkii. A whole herd of the giant hadrosaurs emerge from the forest, prompting the young Hadrosaurus to flee. These gentle giants pose no threat to the smaller hadrosaur, but instead use their bulk to tip over trees and defend themselves.

The herd of Ornithotarsus is on their way to the highlands, where they will graze on the various plants which make up the highland’s plains. But there’s a catch. The wet season, while giving life to the plants the Ornithotarsus herd will feast on, leaves the highlands wet and cold, no place for an exposed hadrosaur. These hadrosaurs, however, have a remarkable adaptation. Unlike the hadrosaurs of the lowlands, who bear scutes over their body save for the occasional bristle-like proto-feather ancestral to the order ornithischia, a thick pelt of modified proto-feathers insulate the Ornithotarsus immanis while they occupy the highlands. They are, indeed, woolly hadrosaurs.

But their are other dangers awaiting the O. immanis on their journey to the highlands. packs of dromaeosaurids occupy the highlands year-round, and harass the herd of hadrosaurs in an attempt to pick off the young. Harsh storms also pose a threat, and often young, old, and weak hadrosaurs are separated from the herd during these tempests, and are left to find their way through the woods back to the herd or die in the dark forests below the bald peaks of the mountains.

The herd advances on. So far, only two individuals have been separated from the herd, neither of which being juveniles. The herd is almost to the end of their 170 mile, 3 day long, 2500 foot verticle climb to reach the highlands. There is, however, one more challenge they must face. The rock fields of the outer highlands are a nesting site for large azhdarchid pterosaurs. With wingspans of up to 30 feet, and heads shaped like swords, these flying archosaurs can injure even adult Ornithotarsus. The hadrosaurs have also developed a trick for dealing with the pterosaurs. Ornithotarsus bellow as a means of communication, but they also use their calls as a means of intimidation. The azhdarchids, for one, are terrified of the hadrosaurs’ loud bellows, and take to the skies as soon as they hear the first call, leaving the herd to safely pass between the rock fields.

The herd finally arrives at the highlands. In front of them lie the highland plains, and they waste no time in indulging themselves, the wind howling across the expanses of plant littered earth.

What we have of Ornithotarsus consists of a partial tibia, fibula, astralagus, and calcaneum (Prieto-Marquez, Weishampel, & Horner, 2006). These remains possibly hail from the Woodbury Formation of New Jersey (Colbert, 1948). The animal itself was apparently enormous (Colbert, 1948), with an estimated length of 39 feet (Holtz, 2012). In his 1948 paper, Edwin Colbert described the animal as follows: “This seemingly represents a very large hadrosaurian, larger then any others known from the eastern Cretaceous, but until additional material is forthcoming nothing definite can be said concerning this supposed species.” Sentences like that get me excited. If Ornithotarsus was the large hadrosaur Colbert suspected it of being, it would be the largest known terrestrial-animal from the Woodbury Formation.

Ornithotarsus consists of one species, O. immanis. Like many other dinosaurs from the Eastern US, it has been considered a nomen dubium by some workers (Prieto-Marquez, Weishampel, & Horner, 2006), and a synonym of Hadrosaurus foulkii as well (Baird & Horner, 1977) (Weishampel & Horner, 1990) (Horner et. al., 2004) (Weishampel, 2006). Colbert (1948) makes a good point, noting that the fragmentary nature of the Ornithotarsus immanis material causes anything said about the animal to be tentative at best. So what exactly can we say about O. immanis, even if the statement is tentative?

If Ornithotarsus immanis does hail from the Woodbury Formation, it is likely this gargantuan hadrosaur co-existed with the smaller H. foulkii. These animals might have co-existed by exploiting different food sources in the same I have suggested before concerning other hadrosaur genera. So what of (tentative) classification? Prieto-Marquez, Weishampel, & Horner, (2006) classified Ornithotarsus immanis as an indeterminate hadrosaurid, and based on Colbert’s statement, this seems to be the best we can do in terms of the classification of Ornithotarsus immanis until more complete specimens are discovered.

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

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

Besides Hadrosaurus, a variety of other animals are known from the Woodbury Formation. Hence the fact that the Woodbury Formation is a marine deposit, specimens of the shark Scapanorhynchus texanus, the fish Enchodus, and the sea turtle Catapleura repanda have been collected from the formation (Gallagher, 1993).

Scapanorhynchus texanus teeth. Photo by the author, 2015.

Scapanorhynchus texanus teeth. Photo by the author, 2015.

Ornithotarsus immanis (if the remains do persist to the Woodbury Formation) is also the temporally oldest hadrosaur I’ve discussed so far. The Woodbury Formation is estimated to have been deposited between 80.5 and 78.5 million years ago (Gallagher, 2005). That beats out Hypsibema crassicauda of the Ellisdale site (=Marshalltown Formation, ~72 million years ago). The Hypsibema of the James King Marl Pits (= Black Creek Formation, ~84.9-70.6 million years ago) may have existed at the same time as Ornithotarsus. 

O. immanis was but one of the first giant hadrosaurs of the continent Appalachia. Hadrosaurs would thrive until the end of the Cretaceous, diversifying into a menagerie of forms on multiple continents. The fate of Ornithotarsus would be burial at sea, its remains eroding away until nothing but fragments remained to be found.

Ornithotarsus immanis by the author. Pencils on paper, 2015.

Ornithotarsus immanis by the author. Pencils on paper, 2015.

For more on gigantic hadrosaurids, see these articles:

Antediluvian Beasts of the East : Hypsibema missouriensis 

Antediluvian Beasts of the East : Hypsibema crassicauda 

References 

1. Prieto−Márquez, A.; Weishampel, D. B.; Horner, J. R. .2006. “The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus.” Acta Palaeontologica Polonica 51(1): 77–98. 

2.Colbert, E.H.  .1948. “A hadrosaurian dinosaur from New Jersey.” Proceedings of the Academy of Natural Sciences of Philadelphia 100: 23–27.

3.Holtz, T. R. Jr; Rey, L. V. .2007. Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House. (Updated during 2012) link: PDF .

4. Baird, D.; Horner, J. R. .1977.” A fresh look at the dinosaurs of New Jersey and Delaware.” The Bulletin of the New Jersey Academy of Science 22(2):50. 

5. Weishampel, D. B. ; Horner, J. R. .1990. “Hadrosauridae.” In D. B. Weishampel, H. Osmolska, and P. Dodson (eds.), The Dinosauria. Berkeley: University of California Press. p. 534-561.

6. Weishampel, D. B. .2006. “Another look at the dinosaurs of the East Coast of North America.” III Jornadas Internacionales sobre Paleontología de Dinosaurios y su Entorno, Salas de los Infantes, Burgos, Spain. Colectivo Arqueológico-Paleontológico Salense Actas:129-168.

7.Gallagher, W. B. .1993. “The Cretaceous/Tertiary mass extinction event in the North Atlantic coastal plain.” The Mosasaur 5:75-154

8. Gallagher, W. B. .2005. “Recent mosasaur discoveries from New Jersey and Delaware, USA: stratigraphy, taphonomy and implications for mosasaur extinction.” Netherlands Journal of Geosciences 84(3): 241.

Antediluvian Beasts of the East : Hypsibema missouriense

It’s the wet season, and flocks of Ornithomimus antiquus pour down into the lowlands from the Appalachians, their feathery bodies glimmering in the sun. The flocks have been migrating through the Appalachian mountains for months, and they’re ready to rest. Predators also arrive with the rains. Pesky dromaeosaurid packs harass the Ornithomimus, picking off the weak and the vulnerable. However, the dromaeosaurs pose no threat to the largest animals of the lowlands…

Enter Hypsibema missouriense. H. missouriense is the westernmost species of Hypsibema, and the largest animal present in the lowlands. These gigantic hadrosaurs form small herds which migrate across the plains, stripping trees and shrubs of their leaves, fruits, and seeds. Their large size means H. missourense are almost immune from attacks by predators, but the wet season brings new threats to the herd, including theropods with bigger bodies and bigger appetites.

The largest predators to come with the start of the wet season are the dryptosaurs. Full grown adults can even take down a Hypsibema missouriense, and many of the gigantic hadrosaurs have scars from fights with these killers. Armed with 3-clawed hands, a mouthful of serrated teeth, and feet like those of an eagle, these dryptosaurs are well-armed carnivores.

It’s midday in the lowlands, and a juvenile dryptosaur descends from its home on an outcrop to a nearby lake. Unfortunately for the young carnivore, a herd of Hypsibema missouriense have stopped to cool off, and do not intend to share the water. The hadrosaurs spot the juvenile, and start to bellow aggressively, signaling that they’ll charge. The juvenile knows not to instigate the titanic dinosaurs, and retreats to the safety of the adult members of its pack.

Hypsibema missouriense is the better studied and more-well known of the two Hypsibema species. Designated as the State Dinosaur of Missouri in 2004 (See reference 1 for more details), this dinosaur was originally mistaken for a sauropod (Gilmore & Stewart, 1945). This attests to the size of the known bones of H. missouriense. All the fossil caudal vertebrae of this animal in the Smithsonian’s collection are almost 10 centimeters (3.9 inches) in length.

The size of H. missouriense‘s caudal vertebrae suggest an animal of similar size to H. crassicauda. However, none of the H. missourense caudal vertebrae above equate to 10 centimeters in length, whereas the caudal vertebrae of the Hypsibema crassicauda type specimen does (the H. crassicauda vertebrae is actually slightly longer then 10 centimeters. Go check out my post here for an image of the type specimen). The longest vertebrae in the image above (rightmost row, second down) comes in at approximately 9.8 centimeters in length. If we compare that with this 10 centimeter caudal vertebrae attributed to H. crassicauda, we realize that the length of the H. missouriense specimen is 96% of the H. crassicauda specimen. Using the length determined by Holtz and Rey (2007) for H. crassicauda (I should note that Holtz and Rey refer to H. missouriense as Parrosaurus, which was placed in  the genus Hypsibema by Baird & Horner (1979)), which they determined was 49.2 feet, we can make an approximate estimate of the length of the H. missouriense holotype. We find a length of 47.2113 feet (96% of 49.2 feet) for the holotype of H. missouriense. That’s slightly smaller then H. crassicauda , but still gigantic for a hadrosaur.

The caudal vertebrae above aren’t the only material we have from H. missouriense. A fragmentary dentary and predentary are known from this animal (Weishampel et. al., 2007)(Check out this page at the Bollinger County Museum’s website to see the partial dentary), as well as some phalanges (see below). From the more complete remains of H. missouriense, we can better understand how the giant hadrosaurids of Appalachia lived.

During the time of Hypsibema missouriense, Missouri was situated in the southwest of Appalachia. Here, the Appalachians gave way to lowlands, which eventually dipped into the Western Interior Seaway.

75 million years ago (Campanian Stage of the Late Cretaceous) the Appalachians were eroding away. The elements slowly chipped away at these mountains, almost flattening them into the lowlands they gave way to. H. missouriense would have been witness to the last of the Cretaceous Appalachian mountains.

H. missouriense itself hails from the Chronister site, a Campanian age deposit, which, in some places, constitutes as a bone bed (Fix & Darrough, 2004). During the Campanian, the Chronister site was a body of fresh water, possibly some sort of lake or wetland (Fix & Darrough, 2004). The Chronister site is very special, as it is the only locality in Missouri which produces terrestrial vertebrate remains dating to the Mesozoic (Fix & Darrough, 2004). Among the vertebrates are turtles, such as Adocus, the large amphibian Habrosaurus, and the crocodilian Leidyosuchus (Fix & Darrough, 2004). Along with H. missouriense, dromaeosaurids and tyrannosaurids make up the dinosaur fauna (Fix & Darrough, 2004). What interests me about this site, however, is its location on the western coast of Appalachia 72 million years ago.

Many Late Cretaceous localities, such as the Ellisdale site (New Jersey) and Phoebus Landing (North Carolina), have yielded the remains of not only dinosaurs, but turtles, amphibians, lizards, fish, and other vertebrates. When it comes to the fossil record from western Appalachia (I am referring to the continent), we aren’t so lucky. The Chronister site gives us the unique opportunity to study what life was like on the eastern shores of the Western Interior Seaway. Yet Chronister’s close proximity to this inland sea might have caused the downfall of its native residents. When this seaway pulled a reverse-Moses, the dinosaurs of Chronister were right there in the midst of Laramidian species, some of which may have outcompeted natives like Hypsibema missouriense. Of course, we can’t be sure what happened, as we simply do not have localities in the Central and Midwestern US which preserve Maastrichtian dinosaur bones from Appalachia. For now, the fate of western giant hadrosaurids like H. missouriense is a mystery.

Although we might never know what eventually happened to the giant hadrosaurids of western Appalachia, the future looks positive for the Chronister dig site. Excavations of this locality are currently being conducted by the Bollinger County Museum of Natural History. New specimens are constantly being unearthed, and the site’s bone bed will surely continue to yield exciting vertebrate fossils, along with those of plants and invertebrates. The secrets of Appalachia’s far west are finally being revealed.

Hypsibema missouriensis faces off against a young dryptosaur. Illustration by the author. Colored pencils on paper, 2015.

Hypsibema missouriensis faces off against a young dryptosaur. Illustration by the author. Colored pencils on paper, 2015.

For more on gigantic hadrosaurids and Appalachian localities, see these articles:

Antediluvian Beasts of the East : Hypsibema crassicauda

The Home of Some Antediluvian Beasts of the East : Ramanessin Brook 

References

1. The State Dinosaur”. State Symbols of Missouri. Missouri Secretary of State. URL: http://www.sos.mo.gov/symbols/symbols.asp?symbol=dino. Accessed June 28, 2015.

2. Gilmore, C. W.; Stewart, D. R. .1945. “A New Sauropod Dinosaur from the Upper Cretaceous of Missouri”. Journal of Paleontology 19 (1): 23–29.

3. “Hypsibema missouriensis” Collections Search Center, Smithsonian Institution. Smithsonian Institution. URL: http://collections.si.edu/search/results.htm?q=Parrosaurus . Accessed June 28, 2015.

4. “Hypsibema crassicauda” Collections Search Center, Smithsonian Institution. Smithsonian Institution. URL: http://collections.si.edu/search/results.htm?q=Hypsibema+crassicauda . Accessed June 28, 2015.

5. Baird, D.; Horner, J. R.  .1979. “Cretaceous dinosaurs of North Carolina”, Brimleyana 2: 1-28.

6. Weishampel, D. B.; Dodson, P.; and Osmólska, H. (eds.). 2007. The Dinosauria, 2nd Edition. Berkeley: University of California Press. p. 443.

7. “Hypsibema missouriense” Collections Search Center, Smithsonian Institution. Smithsonian Institution. URL: http://collections.si.edu/search/results.htm?q=Hypsibema%20missouriense&tag.cstype=all . Accessed June 28, 2015.

8. Fix, M. F.; Darrough, G. .2004. Dinosauria and associated vertebrate fauna of the Late Cretaceous Chronister site of southeast Missouri.” Geological Society of America Abstracts with Programs 36 (3): 14.

The Home of Some Antediluvian Beasts of the East : Ramanessin Brook

The coastal seas surrounding Appalachia left behind some of the best preserved fossil specimens in all of the East Coast. One state in particular is famous for its Cretaceous Marine fossils: New Jersey. Every year, private collectors and museum paleontologists alike flock to New Jersey to uncover ancient bones left behind by creatures which lived around 70 million years ago. One of the most famous site is Ramanessin Brook, where not only Cretaceous marine fossils but also Pleistocene fossils can be found.

Commonly, fossils from the Navesink and Wenonah/ Mt. Laurel Formations are found in the brook, providing a glimpse into the ancient past of New Jersey. Fossils dating from the Pleistocene Ice Age are also found in the brook, giving this site a bit of variation in its fossil contents. Ramanessin Brook is known for one thing in particular: shark teeth. Exquisitely preserved shark teeth are a dime-a-dozen when it comes to this place. Although seemingly nothing compared to localities in the west, sites like Ramanessin brook offer us a lot of information on the ancient sea life of the Western Atlantic Ocean.

Scapanorhynchus texanus teeth collected Ramanessin Brook, NJ.  Photo by the author, 2015.

Check out these pretty chompers! Scapanorhynchus texanus teeth collected Ramanessin Brook, NJ. Photo by the author, 2015.

Invertebrate fossils are also found in the sediments of the brook. Partial ammonite shells, belemnite guards, and even giant oyster shells are pretty common at the brook. Here are a selection of invertebrate fossils:

An ammonite carapace collected at Ramanessin Brook. Note that this is a sliver of the whole shell of the ammonite. This carapace fragment most likely belongs to Placenticeras sp. (meeki?), but might also be that of a Sphenodiscus sp. Photo by the author, 2015.

An ammonite carapace collected at Ramanessin Brook. Note that this is a sliver of the whole shell of the ammonite. This carapace fragment most likely belongs to Placenticeras sp. (meeki?), but might also be that of a Sphenodiscus sp. Photo by the author, 2015.

Here is a piece of matrix with some miscellaneous shell fragments and shell imprints. Boy was this tricky to prep! Photo by the author, 2015.

Here is a piece of matrix with some miscellaneous shell fragments and shell imprints. Boy was this tricky to prep! Photo by the author, 2015.

Vertebrate body fossils are even more common then those of invertebrates at Ramanessin Brook. By far the most common are shark teeth. During this trip, shark teeth from at least 5 different species of shark were collected. Common teeth include those of Archaeolamna kopingensis kopingensis Squalicorax kaupi, and Scapanorhynchus texanus. What’s especially interesting is that S. texanus, unlike its modern relative, lived in coastal waters. S. texanus is also the largest known species of Scapanorhynchus. 

Scapanorhynchus texanus lateral tooth. Photo by the author, 2015.

Scapanorhynchus texanus lateral tooth. Photo by the author, 2015.

Porbeagle sharks are represented by a couple genera, namely Archaeolamna kopingensis kopingensis and Cretodus borodini. These were both mid-sized sharks, with A. kopingensis kopingensis reaching 10 feet in length and C. borodini peaking at 7 feet from snout to tail.

Archaeolamna kopingensis kopingensis teeth. Photo by the author, 2015.

Archaeolamna kopingensis kopingensis teeth. Photo by the author, 2015.

The largest sharks in these waters were Squalicorax pristodontus. Only one tooth of this shark was found during my trip. These guys could reach up to 20 feet in length. Even these sharks, however, weren’t the largest predators in the sea, with large mosasaurs like Mosasaurus and Prognathodon also calling the west Atlantic home (Gallagher, 2005).

The ecosystem the Navesink and Mt. Laurel/ Wenonah Formations represent is a coastal sea. As evidenced by the shark teeth above, there was a high diversity of sharks in the Western Atlantic during the Late Campanian/ Early Maastrichtian.

These fossils are also a tricky task to identify in some circumstances. Not much has been published recently on Eastern US deposits (one of the reasons I started the series Antediluvian Beasts) , and so to accurately identify these fossils, we must look at the old literature (I’m taking literature by Joseph Leidy) and the new(ish). I will have much more to say about this site in the future, but for now I wanted to give a brief introduction. For a little more on the animals of Ramanessin Brook, refer to these past articles:

Antediluvian Beasts of The East: Scapanorhynchus texanus 

References 

1.Gallagher, W. B. . 2005. “Recent mosasaur discoveries from New Jersey and Delaware, USA: stratigraphy, taphonomy and implications for mosasaur extinction.”  Netherlands Journal of Geosciences 84(3):241-245

Antediluvian Beasts of the East: Hypsibema crassicauda

The sun distorts the woodland, drying the earth and leaving trees with a greedy countenance. It’s migration season, and the herd marches across the parched landscape with the might of an army. The animals themselves are primarily Hadrosaurus, which bellow to ward off unwanted attention. Then there are the nodosaurs. Nodosaurs aren’t doing very well on Laramidia during the Campanian Stage of the Late Cretaceous, but on Appalachia, they thrive. Armed to the eyelids with spikes and scutes, they pose quite a challenge for predators. Lophorhothon, another type of hadrosaur, is also found within the herd, but these animals are few and far between. None of these dinosaurs, however, are as impressive as Hypsibema crassicauda. The larger of the two species of HypsibemaH. crassicauda can attain lengths of around 50 feet, making the species one of the largest hadrosaur genera, and certainly the largest species of dinosaur present on Appalachia. One of the largest individuals in the herd is a fourteen year old female, who measures 45 feet from beak to tail. Alongside her is another female who is only slightly smaller at 42 feet in length. They triumphantly lead the herd of dinosaurs across the plain, pridefully stomping across the cracked earth below them, as if they were untouchable. The continent of Appalachia, however, is a very dangerous place for a herbivore, and much danger awaits the heard.

To reach a new browsing location, the herd must first cross a thin strip of beach. But there’s death in the water. The lone carcass of a Claosaurus is spotted among the waves, alarming the already-weary herd. They know, however, that they must march on, and they forget about the rotting body.

A few hours pass, and the herd is almost to the forest. Suddenly, a giant Deinosuchus rugosus rushes out of the water, catching a subadult Hadrosaurus between its jaws. Another Hadrosaurus, startled at the sight of the crocodile, bellows to alarm the rest of the herd. A large Hadrosaurus bellows back, trying to scare away the Deinosuchus, which pulls the juvenile hadrosaur down into the abyss.

The Hypsibema are also on guard, but for a different reason. They’ve spotted a lone male Dryptosaurus, and, although he poses little threat, they are weary of him, grunting and snorting to scare the tyrannosaur away. Undaunted, the Dryptosaurus goes about on his patrol, leaving the hadrosauroid giants to browse on the vast expanses of Spruce and Redwood trees which make up the forest behind them.

Hypsibema crassicauda is one of the largest known hadrosaurs. At an estimated 49.2 feet in length (Holtz and Rey, 2007), this member of the hadrosauridae (Horner et. al., 2004) was most likely the largest herbivore in its ecosystem. The holotype, a fragmentary specimen discovered at the King James marl pits in North Carolina, consists of a caudal vertebra, a humerus, a tibia and a metatarsal (Cope, 1869).

The material belongs to a huge hadrosaur. When we look at this Smithsonian specimen of a caudal vertebrae of the animal (which is slightly smaller then the caudal vertebrae included in the holotype), we find the vertebra’s length is approximately 10 centimeters (3.9 inches for the metric-system impaired). If we compare that size with that of a large Edmontosaurus annectens caudal centrum (sadly in private hands), we realize that the Hypsibema crassicauda caudal centrum is approximately 25% larger than that of the Edmontosaurus. Knowing that large E. annectens could reach around 11.9 meters (Sues, 1997), we can estimate the size of H. crassicauda. To do this, we find 25% of 11.9 meters (2.975 meters) and add that to the original 11.9 meters. We end up with 14.875 meters, or 48.8025 feet. Based on the estimated weight of related animals, I also estimate H. crassicauda to have weighed around 17-20 tons. That’s one large hadrosaur!

However, the size estimation method I used is certainly flawed. As Hypsibema crassicauda was a way more basal hadrosaurid than E. annectens, scaling the former from the latter is faulty, due to each of the animal’s different morphological features. Another issue to this method is that scaling an animal from a single bone gives inaccurate answers. Yet Holtz and Rey (2007) also found H. crassicauda to be around 50 feet long and 17 tons (they found it to be 49.2 feet long and “two Elephants” (=14 tons) in weight). If Hypsibema crassicauda did attain this size, it wasn’t just a large hadrosaur, but one of the largest.

I only know of two other non-dubious hadrosaurid taxa which have been estimated to be larger then 49.2 feet in length and 14 tons in weight: Shantungosaurus giganteus at an estimated 54 feet in length (Zhao et. al., 2007)(if Ji et. al., 2011 were right in there analysis that Zuchengosaurus maximus is a junior synonym of s. giganteus) and 18 tons in weight (Horner et. al., 2004), and Magnapaulia laticaudus at between 49.2 and 54.1 feet in length with a weight of up to 25 tons (Morris, 1981). A more recent study, however, has estimated the latter dinosaur to be around 41 feet in length (Prieto-Márquez et. al., 2012). If Prieto-Márquez et. al. (2012) are correct in their size estimate of MagnapauliaHypsibema may be the longest known North American hadrosaurid, and possibly rivals Shantungosaurus giganteus as the longest hadrosaur known to science.

Like other hadrosaurids, H. crassicauda was designed to be an efficient eater. It has even been suggested that hadrosaurids could browse for food sources up to 4 meters above the ground (Mallon & Anderson, 2013). This would make sense for a giant hadrosaurid such as Hypsibema crassicauda, whose body would require an ample daily food supply. I imagine H. crassicauda as the elephant of Appalachia, browsing on anything it could get its beak around. The habitat of this dinosaur would have been woodland, where it would have had a food supply to match its appetite.

The habitat of Hypsibema crassicauda may have been similar to this. Beaver Lake, Colorado. Photo by the author, 2015.

The habitat of Hypsibema crassicauda may have been similar to this. Beaver Lake, Colorado. Photo by the author, 2015.

The size of Hypsibema crassicauda also interests me for another reason. Along with Hypsibema crassicauda, two other species of gigantic basal hadrosaurid are known from the Eastern United States. These are the gigantic Hypsibema (=Parrosaurus) missouriensis from Missouri (estimated at around 50 feet and 14 tons as well (Holtz and Rey, 2007), although this animal seems to be smaller then H. crassicauda) and Ornithotarsus immanis from New Jersey, a possible synonym for Hadrosaurus foulkii (Prieto-Marquez, A., Weishampel, D. B. & Horner, J. R., 2006) (which is estimated to be 39.6 feet in length and 7 tons in weight (Holtz, 2012). The location of these animals (did I mention Hypsibema crassicauda material is reported to have been found in NJ?) shows that gigantic hadrosaurids in the 40-50 foot, 10-20 ton size range were very widespread across Appalachia during the Late Cretaceous, whereas on Laramidia, only one hadrosaur taxa has been estimated to be around that size range, the lambeosaurine Magnapaulia laticaudus. And even these lambeosaurine giants had competition. The morphological similarities of lambeosaurine and ceratopsid dinosaurs might have been the reason that they weren’t able to coexist for long periods of time due to competitive exclusion (Mallon & Anderson, 2013).

So why were there so many gigantic basal hadrosaurids on Appalachia? I believe the reason was the lack of the ceratopsids and highly derived hadrosaurids. Ceratopsids were most likely low-level browsers, using their strong beaks to ingest tough plant matter (Mallon & Anderson, 2013), and lambeosaurines probably occupied similar regions of morphospace (Mallon & Anderson, 2013). The possible scarcity of these groups on Appalachia (so far, we haven’t found any ceratopsian remains on the East Coast, and lambeosaurine remains, though present (Gallagher, 2002) are seldom found, and only from Maastrichtian deposits) might have allowed more basal forms to thrive.

Could the absence Ceratopsid and derived hadrosaurid dinosaurs on Appalachia allow basal hadrosaurids to thrive and grow to gigantic size? Photo: Skull of a Triceratops. Photo by the author, 2015.

Could the absence of ceratopsid and derived hadrosaurid dinosaurs on Appalachia allow basal hadrosaurids to thrive and grow to gigantic size?
Pictured: Skull of a Triceratops, a ceratopsid dinosaur. Photo by the author, 2015.

And yes, I know what you are thinking:

So what about saurolophinae? You said derived hadrosaurs earlier, not just lambeosaurines.

A couple of possible saurolophine dinosaurs are known from Appalachia. I have heard that the Alabama taxon Lophorhothon atopus was suggested to be a saurolophine, but only as a juvenile Prosaurolophus. More recent analyses have concluded that L. atopus is a basal hadrosauroid (Prieto-Marquez & Salinas, 2010). Although some have suggested the presence of Edmontosaurus sp. at the Ellisdale site (Gallagher, 1993), a Marshalltown Formation exposure which is around 72 million years old, this dinosaur’s presence at Ellisdale is tentative at best, and the reported  “Edmontosaurus sp.” remains are probably just those of a Hadrosaurus or of an indeterminate hadrosaur.

The skeleton of Edmontosaurus, a saurolophine dinosaur, at the Yale Peabody Museum. Photo by the author, 2014.

The skeleton of an Edmontosaurus, a saurolophine dinosaur, at the Yale Peabody Museum. Note the featherless Deinonychus photobombing. Photo by the author, 2014.

Another question might be about competitive exclusion between East Coast nodosaurs and giant hadrosaurids. Mallon & Anderson (2013) also covers this for us. Their analysis concluded that ankylosaurs were the least likely to compete with other large herbivores.

If the lack of ceratopsids and derived hadrosaurs is what allowed the large basal hadrosaurids of the East Coast to thrive, then the presence of these groups might have also caused the downfall of hadrosaurian giants like Hypsibema crassicauda. The Navesink Formation, a Maastrichtian-age deposit, bears both the remains of (possible) lambeosaurines (Gallagher, 2002) and smaller, more basal hadrosaurids, such as Hadrosaurus (Gallagher et. al., 1986), found on Appalachia prior to the closing of the Western Interior Seaway (AMNH 7626, attributed to Hadrosaurus, from the Campanian, for example). It seems to me that the immigration of west-originating dinosaur groups to the Eastern US is correlated with the disappearance of large basal hadrosaurids on Appalachia. The giant basal hadrosaurids of Appalachia were simply out-competed. If lambeosaurines were indeed migrating to the Eastern US, it might also have been the case that native East US forms headed westward. The end result would be the odd giant basal hadrosaur in a western Maastrichtian deposit, like Hell Creek. Others have also speculated about the presence of these animals in the west.  These animals must have been very rare occurrences, though, as I do not know of any dryptosaur and/or giant basal hadrosaurid remains reported from Hell Creek or any other western Maastrichtian deposits. If ACDs (Alien Coast Dinosaurs is what we will call these migrants from now on) existed in both the west and the east, we would be looking at a cross-continental dinosaur migration occurring in the time range of 2-3 million years. I will talk more about this concept in later installments of Antediluvian Beasts, so for now, keep this idea in mind.

Many other types of animals uncommon or absent in the west coexisted with Hypsibema crassicauda. On Appalachia, the dryptosaurs were among the top terrestrial predators, whereas in the west, derived tyrannosaurids ruled the roost. We know H. crassicauda existed alongside dryptosaurs due to the presence of H. crassicauda at Ellisdale (Grandstaff et. al., 1992) alongside Dryptosaurus sp. (Grandstaff et. al.,1992). It’s possible that the gargantuan hadrosaur might have even fallen prey to the dryptosaurs present in its environment.

So what were the dynamics of Hypsibema crassicauda’s environment, exactly? In the southern part of H. crassicauda’s known range, it would have co-existed with other hadrosaurs, such as Hadrosaurus minor (Lull & Wright, 1942), and theropods such as Ornithomimus antiquus (Baird & Horner, 1979). At Ellisdale, the gigantic hadrosaurid would have shared the woodland with Hadrosaurus (Grandstaff et. al, 1992), Ornithomimus (=Coelosaurus)(Denton & Gallagher, 1989), and the predatory theropod Dryptosaurus (Grandstaff et. al., 1992).  The variation of sizes among the hadrosaurs present in the environments mentioned above (Hypsibema crassicauda grew to 48.8 feet in length, whereas a Hadrosaurus would reach 26 feet in length (Holtz, 2012)) suggests that niche partitioning might have evolved between these dinosaur genera. Hadrosaurus could have been the low-browsing deer to Hypsibema’s variety-browsing elephant. So many hadrosaur species of varying sizes from the Late Campanian and Early Maastrichtian of the East Coast are known (i.e. Hadrosaurus foulkii, Hadrosaurus cavatus, Ornithotarsus immanis, Hadrosaurus minor, etc.), that it is hard to imagine the absence of niche partitioning among these dinosaurs.

Hypsibema crassicauda‘s kind would survive until the end of the Cretaceous, with forms like Hadrosaurus minor surviving into the Maastrichtian, their remains deposited in the Navesink Formation (Gallagher et. al.,  1986). The giant basal hadrosaurids, however, would decrease in number, being replaced by the lambeosaurines and edmontosaurinines which were able to arrive from the west as the Western Interior Seaway had closed. The KT extinction event finally sealed the giant hadrosaurs’ fate, their bones left to dry in the hot, crackling dirt.

Hypsibema crassicauda by the author. Colored pencils on paper, 2015.

Hypsibema crassicauda by the author. Colored pencils on paper, 2015.

 References 

1. Holtz, T. R. Jr.; Rey, L. V. .2007. Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages. New York: Random House. p. 409. 

2. Horner, J. R.; Weishampel, D. B.; Forster, C. A. .2004. “Hadrosauridae”. In Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.). The Dinosauria(2nd ed.). Berkeley: University of California Press. pp. 438–463.

3. Cope, E. D. .1869. “Remarks on Eschrichtius polyporus, Hypsibema crassicauda, Hadrosaurus tripos, and Polydectes biturgidus.” Proceedings of the Academy of Natural Sciences of Philadelphia 21: 191-192.

4. “Hypsibema crassicauda” Collections Search Center, Smithsonian Institution. Smithsonian Institution. URL: http://collections.si.edu/search/results.htm?q=Hypsibema+crassicauda . Accessed June 10, 2015.

5. Sues, H-D. (1997). “Ornithopods”. In Farlow, James O., and Brett-Surman, Michael K. (eds.). The Complete Dinosaur. Bloomington: Indiana University Press. p. 338.

6. Zhao, X.; Li, D.; Han, G.; Hao, H.; Liu, F.; Li, L.; Fang, X. .2007. “Zhuchengosaurus maximus from Shandong Province.” Acta Geoscientia Sinica 28 (2): 111–122.

7. Ji, Y., Wang, X., Liu, Y., and Ji, Q. .2011. “Systematics, behavior and living environment of Shantungosaurus giganteus (Dinosauria: Hadrosauridae).” Acta Geologica Sinica 85(1): 58-65.

8. Morris, W. J. .1981. “A new species of hadrosaurian dinosaur from the Upper Cretaceous of Baja California: ?Lambeosaurus laticaudus.” Journal of Paleontology 55(2): 453–462.

9. Prieto-Márquez, A.; Chiappe, L. M.; Joshi, S. H. .2012. Dodson, Peter, ed. “The lambeosaurine dinosaur Magnapaulia laticaudus from the Late Cretaceous of Baja California, Northwestern Mexico.” PLoS ONE 7 (6): e38207.

10. Mallon, J. C.; Anderson, J. S. .2013. “Skull Ecomorphology of Megaherbivorous Dinosaurs from the Dinosaur Park Formation (Upper Campanian) of Alberta, Canada.” PLoS ONE 8(7): e67182.

11. Prieto-Marquez, A.; Weishampel, D. B.; Horner, J. R. .2006. “The dinosaur Hadrosaurus foulkii, from the Campanian of the East Coast of North America, with a reevaluation of the genus.” Acta Palaeontologica Polonica 51: 77-98.

12. Holtz, T. R. Jr; Rey, L. V. .2007. Dinosaurs: the most complete, up-to-date encyclopedia for dinosaur lovers of all ages. New York: Random House. (Updated during 2012) link: PDF .

13. Gallagher, W. B. .2002. “Faunal changes across the Cretaceous-Tertiary (K-T) boundary in the Atlantic coastal plain of New Jersey: restructuring the marine community after the K-T mass-extinction event.” Catastrophic Events and Mass Extinctions: Impacts and beyond. GSA Special Paper 356:291-301.

14. Prieto-Marquez, A.;  Salinas, G. C. .2010. “A re-evaluation of Secernosaurus koerneri and Kritosaurus australis (Dinosauria, Hadrosauridae) from the Late Cretaceous of Argentina.” Journal of Vertebrate Paleontology 30(3): 813-837.

15. Gallagher, W. B. .1993. “The Cretaceous/Tertiary mass extinction event in the North Atlantic coastal plain.” The Mosasaur 5:75-154.

16. Grandstaff, B. S.; Parris, D. C.; Denton, R. K. Jr.; Gallagher, W. B. .1992. “Alphadon (Marsupialia) and Multituberculata (Allotheria) in the Cretaceous of Eastern North America.”  Journal of Vertebrate Paleontology 12(2): 217-222.

18. Lull, S; Wright, N. E. .1942. “Hadrosaurian dinosaurs of North America.” Geological Society of America Special Paper 40:1-242.

19. Baird, D.; Horner, J. R. .1979. “Cretaceous dinosaurs of North Carolina.” Brimleyana 2:1-28.

20. Denton, R. K.; Gallagher, W. .1989. “Dinosaurs of the Ellisdale site, Late Cretaceous (Campanian) of New Jersey.” Journal of Vertebrate Paleontology 9(3, suppl.):18A.

21. Gallagher, W. B.;  Parris, D. C.; Spamer, E. E. .1986. “Paleontology, biostratigraphy, and depositional environments of the Cretaceous-Tertiary transition in the New Jersey coastal plain.” The Mosasaur 3:1-35.

EDIT: The remains of a leptoceratopsid have been reported from the Tar Heel Formation of Cretaceous North Carolina. This shows that ceratopsians were present on Appalachia. However, the presence of leptoceratopsids on Appalachia does not automatically imply that the generally larger ceratopsids were present as well.

Antediluvian Beasts of the East : Tamias aristus

First off, thanks for 300 views this past month! That blows my mind. I hope you enjoy the post, and thanks for reading!  Hike through any forest on the East Coast of the US today, and you’re bound to come across those small, fast sciurids we know as chipmunks. Back during the Pleistocene, however, chipmunks grew to much larger sizes, as evinced by the giant, or “noblest” chipmunk, Tamias aristus. The modern Eastern chipmunk, Tamias striatus, has been found to be T. aristus‘s closest relative (Ray, 1965), suggesting that the genus Tamias has an ancestry in the Eastern US. Based on the bones, T. aristus was around 30% larger then the modern Eastern chipmunk. Try thinking about that next time you go to see one of those cheesy Alvin and the Chipmunks movies! The type specimen of this animal was discovered at Ladd’s Quarry, which is a Pleistocene site in Georgia (Ray, 1965). Pleistocene Ice-Age tapir, Dire wolf, and even peccary fossils have been found at this site. A variety reptiles and amphibians were also present (Holman, 1985). Like the giant beaver Castoroides, which also inhabited the East Coast during the Pleistocene Ice Age (Hulbert et. al., 2014), Tamias aristus represents a super-sized relative of a modern species, which was a common trope during the Late Pleistocene. T. aristus may have had a slightly different lifestyle then its modern day-relative, but their overall skeletal similarities suggest that T. aristus occupied a similar niche. I’ve heard John Alroy estimated Ladd’s Quarry  to be around 300,000 years old based on the presence of the Vero tapir, but I haven’t seen any publications with this information. We can conclude, however, that Ladd’s Quarry represents an interglacial period with higher temperatures present then those of today. This conclusion is based on the presence of wetland animal remains, such as those of the Florida muskrat (Ray, 1967), at the site. Apart from these warmer-climate favoring species, a variety of other animals are found at Ladd’s Quarry which also are observed in the forests of the East Coast today. The Eastern Cottontail, White-tailed deer, and Opossum are just some of the animals which left their remains behind at Ladd’s (Ray, 1967). Larger animals, such as the horse Equus (Ray, 1965) and the giant ground sloth Megalonyx (Ray, 1967) are also present, and probably were the resident megafauna at Ladd’s Quarry during this interglacial period.

The environment which the noblest chipmunk called home would be similar to this modern forest in Connecticut. Photo by the author, 2015.

The environment which the noblest chipmunk called home would be similar to this modern forest in Connecticut. Photo by the author, 2015.

The noblest chipmunk (I’ll be referring to T. aristus as so from now on, as I find the name adorable) may also be known from Ice Age deposits in Florida. I can’t confirm the presence of this animal in Florida for lack of good references. However, the site fossilworks.org indicates T. aristus existed among the fauna of the Florida site Arredondo IIA, which dates to the Sangamonian interglacial stage. If the noblest chipmunk was present in Florida during the Sangamonian, it indicates that the chipmunk was able to survive through glacial periods, and also extends the noblest chipmunk’s temporal range by ~182,000 years (this is all based on if Ladd’s Quarry actually represents a 300,000 year old deposit, which some have argued against) . In Florida, the noblest chipmunk would have co-existed with many of the same species it came into contact with at Ladd’s. But let’s go back to the noblest chipmunk’s niche. As I said above, we think that the noblest chipmunk and the Eastern chipmunk had similar niches. The size of the noblest chipmunk, however, suggests that the noblest chipmunk had a slightly different lifestyle then T. striatus. I hypothesize, like some others, that the noblest was a year-round forager, taking advantage of its contemporaries’ hibernating needs. This lifestyle would equate to the animal possibly having larger fat layer, more hair for insulation in the cold, and an overall more robust body in life in order to withstand the extremes of winter. If this is the case, we might be looking at an effectively “woolly-chipmunk”. Keep in mind however, that this is wild speculation.

An Eastern Chipmunk foraging for Walnuts (Juglans sp.) stops to ponder at its larger relative, the noblest chipmunk Tamias aristus. Illustration by the author. Pencils on paper, 2015.

An Eastern Chipmunk foraging for Walnuts (Juglans sp.) stops to ponder at its larger relative, the noblest chipmunk Tamias aristus. Illustration by the author. Pencils on paper, 2015.

But this chipmunk’s reign as king of the forest floor was not to last. More extreme glacial intervals caused the forests of the East Coast to turn into grasslands. This specialist forager, who possibly depended on a year-round supply of food, slowly ran out of habitat, and eventually succumbed to extinction. The smaller, more adaptable Tamias species survived, an echo of an ancient arms-race. This grassland-killed hypothesis has been inferred by other folks as well, and seems to be our best shot at understanding how the noblest chipmunk’s extinction occurred.

Forests gave way to grassland during glacial periods. If you're an avid paleo-enthusiast, you might recognize that this photo is of Florissant Fossil Beds National Monument. Photo by the author, 2014.

Forests gave way to grassland during glacial periods. If you’re an avid paleo-enthusiast, you might recognize that this photo is of Florissant Fossil Beds National Monument. Photo by the author, 2014.

The noblest chipmunk is just another example of super-specialization eventually causing the extinction of a species. Yet during its heyday, Tamias aristus ruled the roost on the forest floors of Ice-Age Eastern US, its bones still preserving an ancient chipmunk legacy.

References 

1. Ray, .C. E. . 1965. “A new chipmunk, Tamias aristus, from the Pleistocene of Georgia.” Journal of Paleontology 39(5):1016-1022.

2. Hulbert, R.; Kerner, A.; Morgan, G. S. .2014. “Taxonomy of the Pleistocene giant beaver Castoroides (Rodentia: Castoridae) from the southeastern United States.” Bulletin of the Florida Museum of Natural History 53(2):26-43. 3.

3. Holman, J.A. .1985. “Herpetofauna of Ladds Quarry.” National Geographic Research 13: 423-436.

4. Ray, C. E. .1967. “Pleistocene mammals from Ladds, Bartow County, Georgia.” Bulletin of the Georgia Academy of Science 25(3):120-150.

Antediluvian Beasts of the East : Scapanorhynchus texanus

It’s evening, and a number of pycnodont fish called Anomaeodus phaseolus swim above a coral reef in the cold, murky coastal waters of the newly formed Atlantic Ocean. They gracefully zip through the salty water, feasting on any morsel of edible material they can find. But there are bigger, stranger fish in this sea.

Behind a cluster of corals, a silent predator patrols the water, scanning for any signs of movement. Enter Scapanorhynchus texanus. The shark darts from the coral, and snares one of the Anomaeodus in its jaws. For the fish, death is certain , and for the shark, it’s just another successful hunt.

Scapanorhychus was a prehistoric goblin shark, and an extremely successful one at that. The largest species, S. texanus, was a common sight in the Atlantic Ocean during the Late Cretaceous. Fossil teeth and other possible remains of this shark species are found along Eastern US Seaboard, being found within the states of New Jersey (Phillips et. al., 2001) and North Carolina (Case, 1979). The teeth of S. texanus are the largest among all Scapanorhynchus species. When we scale S. texanus by comparing known S. texanus remains with those of the modern goblin shark, we find that S. texanus was around 11 feet in length.

Scapanorhynchus texanus teeth collected Ramanessin Brook, NJ.  Photo by the author, 2015.

Scapanorhynchus texanus teeth collected Ramanessin Brook, NJ. Photo by the author, 2015.

The fossilized anterior teeth of this shark have an elongated main cusp with bilateral roots, perfect for snagging slippery prey. The lateral teeth of the shark are more triangular in shape then the anterior teeth, and are far broader. 

The fossilized remains of this Mitsukurinid shark are  found in coastal deposits (Phillips et. al., 2001), suggesting that this animal occupied the niche of a coastal predator. This is a far different niche from modern goblin sharks, who prefer the ocean depths as their hunting ground. Well-preserved body fossils of some species of Scapanorhynchus show that this shark species also possessed the long, pointed snout and long tail of modern goblin sharks.

Scapanorhynchus texanus lateral tooth. Photo by the author, 2015.

Scapanorhynchus texanus lateral tooth collected at Ramanessin Brook, NJ. Photo by the author, 2015.

The teeth shown above came from “Scaps” which called the coastal plain of New Jersey home. This coastline was home to a variety of other large predators, including mosasaurs such as Halisaurus platyspondylus (Wright, 1988).

The teeth of other sharks which Scapanorhynchus texanus coexisted with at Ramanessin Brook. Photo by the author, 2015.

The teeth of other sharks which Scapanorhynchus texanus coexisted with at Ramanessin Brook. From left to right: Paranomotodon angustidens, Squalicorax kaupi, Archaeolamna kopingensis kopingensis. Photo by the author, 2015.

Teeth from other Scapanorhynchus species are also found in the Middle East (Retzler et. al., 2013), showing that this shark was present on both sizes of the Atlantic Ocean.

Scapanorhynchus texanus and an marine turtle by the author. Colored pencils and Copic markers on paper, 2015.

Scapanorhynchus texanus and an marine turtle by the author. Colored pencils and Copic markers on paper, 2015.

S. texanus was thriving during the Campanian and Maastrichtian stages of the Cretaceous, but this shark’s success was short-lived. Many species of Scapanorhynchus, as indicated by the fossil record, greatly declined in number following the KT extinction. However, this shark wasn’t at the end of its line. The modern goblin shark, Mitsukurina owstoni, is a surviving member of Scapanorhynchus’s lineage and continues to haunt the depths of the ocean today.

 References 

1. Phillips D., Rose E., Pedersen J. 2001. Big Brook Upper Cretaceous Geology and Paleontology. 127 W 83rd Street, New York, NY: The New York Paleontological Society.

2. Case, G. R. . 1979.”Cretaceous selachians from the Peedee Formation (Late Maestrichtian) of Duplin County, North Carolina.” Brimleyana (2): 77-89 [J. Kriwet/W. Glaeser/M. Carrano]

3. Wright KR. 1988. “A new specimen of Halisaurus platyspondylus (Squamata: Mosasauridae) from the Navesink Formation (Maastrichtian) of New Jersey.” Journal of Vertebrate Paleontology 8 (Supplement 3): 29A-30A.

4. Retzler A., Wilson M.A., Avni Y. .2013. “Chondrichthyans from the Menuha Formation (Late Cretaceous: Santonian–Early Campanian) of the Makhtesh Ramon region, southern Israel”. Cretaceous Research 40: 81–89.