http://santiagotalavera.com/tag/hiroyuki-doi Name Meaning: False Lizard
http://c3patriot.com/terms_and_conditions Geologic Era: Triassic
comment j ai rencontre des poissons Location Found: Muschelkalk (Shellbearing Limestone), Brandenburg, Rudersdorf, Germany
regarde ça Estimated Range: Europe, North America, China
Size: 4 meters long
Extinction: 210 million years ago
This tooth is from the forejaw of a semi-aquatic reptile. The teeth in back are a bit shorter, but our tooth is longer and more curved, which is more characteristic of the front teeth of Nothosaurus. There is also a smaller bone present alongside the tooth; perhaps a vertebra or piece of a vertebra. Nothosaurus bears a passing resemblance to later animals like plesiosaurs, though it was not quite as suited to open water life as later marine reptiles.
Nothosaurus probably occupied the same ecological niche as modern seals. It was probably not as adapted to the water as later forms, but could easily feed itself in the shallows. Nothosaurus’ teeth were well equipped to spear small fish, and this probably made up the bulk of its diet. However, remains of other juvenile marine reptiles have been found in the stomach area of a Nothosaurus skeleton, meaning Nothosaurus would not pass up an easy meal. Anything caught in the teeth of Nothosaurus would have found it nearly impossible to break free.
This does not mean that Nothosaurus was invulnerable to predation itself, however. Many marine reptiles and sharks were larger than Nothosaurus, much the same way the many modern skarks and predatory whales outclass seals in size. A way for Nothosaurus to avoid this fate would be to spend a fair bit of its time on land, out of reach of sharks and larger reptiles. However, this would have put Nothosaurus in range of land-based archosaurs (reptiles), many of whom were also larger than Nothosaurus.
One facet of Nothosaurus’ lifestyle that is still debated is how it reproduced. The two prevailing ideas are that it laid eggs or gave life birth. Both ideas have their merits. Access to land meant that Nothosaurus could have easily laid eggs in the sand and kept watch over them at least some of the time. Egg laying would also have been a bit less labor and energy intensive than gestating live young.
On the other hand, analysis of the pelvic region of Nothosaurus showed that it was anatomically capable of giving live birth. Assuming that Nothosaurus did not care for young after birth, the reptile’s responsibility to the young would end the moment they exited the birth canal. Until definitive proof one way or another is found, there will always be debate as to how Nothosaurus reproduced. Later icthyosaurs did give live birth in water (one fossil catching the event in the act); the question is when did live birth come about in marine reptiles.
Full Skeleton: By Elke Wetzig, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2471328
Life Reconstruction: By Nobu Tamura (http://spinops.blogspot.com) – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19459369