I'm a recently graduated marine biology MRes student from the University of Plymouth. I'm currently looking for jobs in the marine biology field, with a particular interest in behavioral research, and marine mammal and sea turtle ecology. This is a blog about things that I find interesting including conservation, marine biology, evolution, and other sciencey things!
Thursday, January 14, 2016
Something Old
Jurassic Park. What a great film right? Dinosaurs are so cool, but they're not the only awesome prehistoric creatures. Today I want to introduce/re-introduce you guys to five ancient non-dinosaur marine creatures that I think are pretty cool.
1.
Machimosaurus rex
This enormous reptile belongs to the superorder Crocodylomorpha, part of the Linnaean classification system scientists use to determine the relatedness of species, which contains all species of crocodilians both living and extinct. Federico Fanti and his colleagues, who discovered the huge fossil in the Tunisian desert, have estimated the total length of the 130 million year old creature at approximately 9.6 meters, or 31 feet long. For reference the largest modern crocodile can be found at the Bhitarkanika Wildlife Sanctuary in Orissa State, India, and measures in just over 7m (23ft). Assuming this figure holds true (scientists are currently awaiting the discovery of a more complete fossil specimen) it would crown this newly discovered species as the largest saltwatercrocodile of all time. However, while gigantic in its own right M. rex didn't even come close to the largest crocodile of all time, Sarcosuchus imperator (also known as Supercroc), which is estimated to have reached lengths of 12m (>39ft).
Sarcosuchus imperator skull next to modern crocodile skull
Fanti described M. rex as having "...stocky, relatively short and rounded teeth." and "...a massive skull capable of a remarkable bite force." This leads paleontologists to believe that the crocodile consumed a wide variety of prey items including prehistoric sea turtles.
2.
Archelon ischyros
Leatherback Sea Turtle (Dermochelys coriacea)
Archelon is an extinct genus of gigantic marine turtles that lived during the Cretaceous period, approximately 70 mya. These turtles are the largest to have ever lived with the biggest fossil measuring in at 4.87m (16ft) from beak to tail, and 3.96m (13ft) from flipper to flipper. In comparison the largest living sea turtle, the leatherback (Dermochelys coriacea) comes in at 2m (6.5ft) from beak to tail and weigh 900kg (2000lbs). Estimates based upon the body composition of leatherbacks, as the most physically similar living species, suggest that A. ischyros would top the scales at over 2721.55kg (3 tons). While modern turtles are omnivorous, with a varied diet from algae to invertebrates and small fish, A. ischyros's large size meant it would most likely not have been able to chase down actively swimming prey. Paleontologists believe that it probably used its broad crushing beak and powerful bite to break through the shells of the large crustaceans and molluscs of its time.
3.
Dunkleosteus terrelli
D. terrelli skull
D. terrelli was essentially what you would get if you mated a tuna with a tank. The largest of the Dunkleosteus genus, these armoured fish lived during the late Devonian period approximately 380-360 mya. Measuring up to 10m (33ft) long, weighing in at 3628.74kg (4 tons) and with a head covered in bony plates up to 5cm (2in) thick D. terrelli was a figurative swimming tank. D. terrelli didn't have teeth, but instead possessed a beak composed of two bony plates which they used to crush their prey. They did this thanks to an ability to open their mouths in 1/15th of a second creating a vacuum to suck prey into their open beak which they could close with an estimate bite force of 8000 psi (pounds per square inch). In comparison the greatest current measured bite force belongs to the saltwater crocodile at 7700 psi, however incidents involving captive killer whales suggest that they may possess a bite force in excess of 19000 psi.
4.
Kronosaurus queenslandicus
Named for Kronos, the leader of the Titans in Greek mythology, K. queenslandicus is a member of the Kronosaurus genus of pliosaurs, an extinct group of marine reptiles that lived during the Jurassic and Cretaceous periods (~200-66 mya). Reaching lengths of 10m (33ft) with teeth that grew up to 30cm (11.8in) K. queenslandicus was a powerful predator which fed upon ancient marine turtles and plesiosaurs. Utilizing the Pilosaurids unique swimming style, similar to that of modern turtles and sea lions but using both fore and hind limbs for locomotion, K. queenslandicus would have been capable of maintaining high speeds for long periods making it difficult for prey to avoid.
5.
Livyatan melvillei
L. melvillei skull w/teeth cast
The final entry on this short list is the aptly named Livyatan melvillei a prehistoric leviathan which fed on smaller whales between 12-13 mya. As the only fossil remnants of L. melvillei to be discovered are a skull and some teeth, total size estimates range from 13.5m (44ft) to 17.5m (57ft) long. In comparison the largest modern sperm whales (Physeter macrocephalus) can reach 20.5m (67ft) although on average the males grow to 16m (52ft). If these estimates are accurate then L. melvillei would be equivalent in size to another ancient sea monster, Carcharodon megalodon. In fact these massive predators shared the oceans for a (relatively) short time with C. megalodon living from 15.9-2.6 mya. Little is known about the hunting strategies of L. melvillei but scientists theorize that it fed on baleen whales which it may have attacked from below similar to C. megalodon and modern Great Whites (Carcharodon carcharias). Alternatively it may have simply used its powerful jaws to catch and crush the smaller whales ribs. The skull shape with its similarities to sperm whales suggests that L. melvillei may have utilized echolocation to hunt.
So those are five non-dinosaur ancient marine creatures that I think are seriously cool. If you enjoyed this post maybe name some prehistoric creatures you think are awesome in the comments (yeah dinosaurs are allowed). Thanks for stopping by!
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