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.