A Tiny Little Terror From Which There Is No Escape

Meet Cronopio:

Skull of Cronopio dentiacutus, based on MPCA 453 and MPCA 454. In dorsal (top), ventral (bottom) and left lateral 9side) views. After Rouguier et al., 2011. Scale bar equals 5 mm.

Now, the name is misleading, at least at first. It sounds like Pinocchio, right? It (cronopio) is a name derived from a term used by author Julio Cortázar for imaginary, bizarre creatures, and this one certainly fits.

Cronopio dentiacutus (literally, “sharp-toothed bizarre creature”) is a sabre-toothed mammal, a member of an otherwise mousey-looking group called dryolestoids known largely from partial fragments of jaw and isolated teeth, and the unique features at the front of the snout are highly unique for a non-eutherian mammal. Sabretoothed mammals exist from nimravid and felid carnivorans, tragulid “mouse deer”, and other artiodactyls including hippopotamids and suinans (boar, domestic pig, peccaries and babirousa, etc.), and they are generally “fierce,” and at least somewhat omnivorous (especially boar and pigs). Marsupials include the large marsupial sabretooth, Thylacosmilus.

This thus represents one of the smallest “tusked” or “sabretoothed” mammals, and its high-crowned but relatively low-cusped posterior molars imply a largely herbivorous diet. While the complete lower and upper tooth rows allow the authors much room to discuss tooth-position variation in dryolestoids, given their unique shapes (large and triangular premolars, low and flattened tribosphenic molars) in other, often very, very incompletely known taxa, many based only on a single or small set of teeth.

The functional use of such teeth are interesting. Pigs use their (primarily lower) tusks to mark territory and during agonistic combat, and tragulids do the same with their upper canines, as in hippopotamids. These teeth are not predatory except in carnivorans, where their function has been debated in its precise role in the killing of prey (summarized recently by Anderson et al., 2011). So it seems more likely, given the shape of the posterior teeth, that Cronopio dentiacutus was an herbivore, and likely used its canines for agonistic displays. It also implies the known specimens with fangs are male, and that fang-less skulls of similar taxa may be females, although the presence of one fanged taxon doesn’t indicate surely that related animals were also fanged.

Andersson, K., Norman, D. & Werdelin, L. 2011. Sabretoothed carnivores and the killing of large prey. PLoS ONE 6(10):e24971.
Rougier, G. W., Apesteguía, S. & Gaetano, L. C. 2011. Highly specialized mammalian skulls from the Late Cretaceous of South America. Nature 479:98-102.

This entry was posted in Paleobiology, Paleontology, Science Reporting and tagged , . Bookmark the permalink.

4 Responses to A Tiny Little Terror From Which There Is No Escape

  1. Fabrizio says:

    What’s the difference(s) among “After Rouguier et al., 2011”, “Modified from Rouguier et al., 2011” and “From Rouguier et al., 2011”?

    • If I edit an image, it’s “modified from.” If it’s lifted whole without change (the entire image, say, or figure), it’s “from”. If I modify the image in some substantive way, such as adding in text or rearranging the elements, I would write “after” or such. It’s inconsistent, and I wasn’t being too careful on the appellation, although it should be “from” in this context.

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