1. Giant extinct caiman breaks constraint on the axial skeleton of extant crocodylians.
- Author
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Scheyer TM, Hutchinson JR, Strauss O, Delfino M, Carrillo-Briceño JD, Sánchez R, and Sánchez-Villagra MR
- Subjects
- Animals, Paleontology, Phylogeny, Alligators and Crocodiles anatomy & histology, Bone and Bones anatomy & histology, Extinction, Biological
- Abstract
The number of precaudal vertebrae in all extant crocodylians is remarkably conservative, with nine cervicals, 15 dorsals and two sacrals, a pattern present also in their closest extinct relatives. The consistent vertebral count indicates a tight control of axial patterning by Hox genes during development. Here we report on a deviation from this pattern based on an associated skeleton of the giant caimanine Purussaurus , a member of crown Crocodylia, and several other specimens from the Neogene of the northern neotropics. P. mirandai is the first crown-crocodylian to have three sacrals, two true sacral vertebrae and one non-pathological and functional dorsosacral, to articulate with the ilium (pelvis). The giant body size of this caiman relates to locomotory and postural changes. The iliosacral configuration, a more vertically oriented pectoral girdle, and low torsion of the femoral head relative to the condyles are hypothesized specializations for more upright limb orientation or weight support., Competing Interests: TS, JH, OS, MD, JC, RS, MS No competing interests declared, (© 2019, Scheyer et al.)
- Published
- 2019
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