The strange teeth of Aerosaurus

Figure 1. Aerosaurus in situ, tracing of same and lateral view. Note the size disparity in the upper and lower teeth -- combined with the strangely curled (hyper recurved) teeth in the uppers -- combined with the very long tooth row extending far behind the orbit. What was this reptile eating?

Figure 1. Aerosaurus in situ, tracing of same and lateral view. Note the size disparity in the upper and lower teeth — combined with the strangely curled (hyper recurved) teeth in the uppers — combined with the very long tooth row extending far behind the orbit. What was this reptile eating?

Just took another look at Aerosaurus. Langston and Reisz (1981) reconstructed them a little more straightened out (see wiki illustration).

Figure 2. Aerosaurus skull reconstructed in dorsal and lateral views. Plus manus and pes and complete specimen in lateral view. This is one of the basalmost synapsids.

Figure 2. Aerosaurus skull reconstructed in dorsal and lateral views. Plus manus and pes and complete specimen in lateral view. Note the rotation of the postorbital from the in situ specimen. This is one of the basalmost synapsids.

The teeth were laterally compressed and >strongly< recurved. The teeth were so highly curved that they seem unable to penetrate flesh and the tooth row extends far behind the orbit. The lower teeth were relatively tiny. Such an arrangement suggests something other than a meat-eating diet, perhaps some sort of filtering or plant-eating. The parasphenoid is uniquely expanded laterally and posteriorly, and bears rows of teeth on ridges. The quadratojugal curved up posteriorly as did the slender mandible. A strange skull indeed.

References
Langston W Jr and Reisz RR 1981. Aerosaurus wellesi, new species, a varanopseid mammal-like reptile (Synapsida: Pelycosauria) from the Lower Permian of New Mexico. Journal of Vertebrate Paleontology 1:73–96.

Aerosaurus/wiki

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9 thoughts on “The strange teeth of Aerosaurus

  1. Yes, if the hooks were exposed. In this case, however, the hooks seem to be curled back against the next tooth with tips not in the “attack” position. Perhaps some other angles will clarify this issue.

  2. Interesting. If the business end of the teeth were exposed and were in any way abrasive (were they?) then they almost certainly served some purpose, i.e. provided an adaptive advantage. If so, then it suggests to me that the filtering hypothesis is unlikely — cf. baleen whales, which are toothless, “the flamingo’s smile” (Gould), etc. Perhaps Aerosaurus was a scavenger and the teeth helped it “scrape” the flesh from a carcass, like a serrated blade. Just thinking out loud.

  3. Why did you use such a blurry photo? I think I’ve seen better ones.

    Anyway, something you can’t see in a photo taken in lateral view is the fact that, as usual in varanopine* varanopids, the teeth are labiolingually flattened and have serrated edges. They strongly remind me of “velociraptorine” teeth. Being so extremely recurved (which is part of what reminds me of “velociraptorines”) makes them a pretty much continuous cutting edge.

    Definitely a carnivore; just not a tyrannosaur-like one that uses widely spaced, relatively straight, banana-shaped teeth to crush bone.

    And why do you call it a reptile?

    * Called “Varanodontinae” in the literature. This is wrong, because “Varanodontinae” includes Varanops.

  4. Thanks, Dave. That clarifies things. It’s a reptile because it descends from Cephalerpeton, the mother of all reptiles. Reptilia has five definitions Gauthier et al., 1988a; Gauthier, 1994; Laurin and Reisz, 1995; deBraga and Rieppel, 1997, Modesto and Anderson 2004). The latest: “the most inclusive clade containing Lacerta agilis Linnaeus 1758 and Crocodylus niloticus Laurenti 1768, but not Homo sapiens Linnaeus 1758” goes to your point, but is paraphyletic because in the large reptile tree, Homo is part of a clade that includes Lacerta and Crocodylus. Amniota = Reptilia.

  5. Not having the original paper or figure in front of me I just thought I’d point out that the lower jaw looks like it has no teeth but instead empty alveoli. I could be wrong since I am exceptionally tired and the picture itself is blurry. Just an observation.

    • Langston and Reisz (1981) report, “Most of the teeth are more strongly recurved than the teeth of any other well known pelycosaur. Enamel surfaces are smooth and there are no carinae on the upper teeth. An additional six long, slender, and recurved teeth occur posterior to these teeth, and ventral to the postorbital bar and the lateral temporal opening in this specimen. It is not clear how these long, curved posterior teeth were used unless the jaws could be very widely opened. The strongly recurved mandibular teeth are smaller, more closely spaced, and more uniform in size than those of the maxilla.”

  6. it descends from Cephalerpeton

    Not in your own tree, where Cephalerpeton and Amniota are sister-groups.

    It is not clear how these long, curved posterior teeth were used unless the jaws could be very widely opened.

    They probably could be opened very widely; that’s the point of drawing the jaw joints so far caudal to the occiput.

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