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Seeing through the eyes of the sabertooth Thylacosmilus atrox (Metatheria, Sparassodonta) Project ID: 000493868 Public
4 Media · 4 Specimens · Creator: Gaillard, Charlène · Managed by: Charlène Gaillard

The evolution of mammalian vision is difficult to study because the actual receptor organs—the eyes—are not preserved in the fossil record. Orbital orientation and size are the traditional proxies for inferring aspects of ocular function, such as stereoscopy, but results are often mixed because other factors are not taken into account. Adaptations for good stereopsis have evolved in living predaceous mammals, and it is reasonable to infer that fossil representatives would follow the same pattern. This applies to the sparassodonts, an extinct group of South American hypercarnivores related to marsupials, with one exception. In the sabertooth Thylacosmilus atrox, the bony orbits were notably divergent, like those of a cow or a horse, and thus radically differing from conditions in any known mammalian predator. Orbital convergence alone, however, does not determine presence of stereopsis; frontation and verticality of the orbits also play a role. We show that the orbits of Thylacosmilus were frontated and verticalized in a way that favored some degree of stereopsis and compensated for limited convergence in orbital orientation. The forcing function behind these morphological tradeoffs was the extraordinary growth of its rootless canines, which affected skull shape in Thylacosmilus in numerous ways, including relative orbital displacement.

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Filtering by: Data Uploader Charlène Gaillard Remove constraint Data Uploader: Charlène Gaillard Organization NMB Life Sciences Collections Remove constraint Organization: NMB Life Sciences Collections
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  ID Part Object Taxonomy Type Date Added Publication Status  
000505068 cranium nmb:c.2526 Thylacinus cynocephalus Mesh 2023-03-21 Restricted Download  
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