Name Meaning: House of Moving Teeth?
Geologic Era: Triassic
Location Discovered: Arizona/New Mexico
Size: Up to 3 meters long (our specimen is from a juvenile)
Estimated Range: Southwestern United States
Extinction Date: Late Triassic
Note: This animal was once classified as Apachesaurus, however, more recent studies have found that Apachesaurus is simply a juvenile of Koskinonodon.
Koskinonodon was probably salamander-like in habits, and does bear a strong resemblance to many modern amphibians. Koskinonodon is classified as a temnospondyl, a group of amphibians that became extinct during the Mesozoic era. Temnospondyls resembled modern amphibians, but with the addition of scales, claws, and sometimes armor plating. It would have coexisted with early dinosaurs such as Coelophysis.
Our specimens may or may not be from the same animal, but they are from the same species. As you can see, the tooth, while small, still is very sharp looking, indicating a predatory lifestyle. The jaw fragment still has several sockets visible, though the teeth themselves are gone. The partial claw is missing its tip, and in life would have been covered in a keratinized sheath, making it even longer and sharper. The vertebra is missing any processes it had in life, but I would guess that it came from the base to the middle of the tail.
On a lark, I recently put the tooth under a microscope. What I saw took me a bit by surprise. Many of the predatory dinosaur teeth show distinct serrations (not unlike the edge of a steak knife) that are not visible macroscopically, but show up beautifully under a microscope. The Koskinonodon tooth showed no such serrations, and had an almost needle-like profile. Clearly, this was a tooth that was not designed for chewing or cutting meat, rather for piercing and holding prey. Such teeth would have been a good adaptation for preying upon insects, which have tough exoskeletons. These exoskeletons would have been no match for the tooth of Koskinonodon.
Life Restoration: By Dmitry Bogdanov – self-made, firstname.lastname@example.org, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3014035
Skeleton: By Lawrence from San Francisco, USA – NewYork200710b 130, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=4209540