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. 2020 Oct 20;8:e10145. doi: 10.7717/peerj.10145

Figure 7. Variation in Tylosaurus premaxillae.

Figure 7

Intraspecific variation of Tylosaurus premaxilla rostrum shape (A and B) and foramina size (C–E). In relatively immature individuals, the premaxillary rostrum is acute in lateral view (A; T. proriger AMNH FARB 4909) and the foramina are large (C; T. nepaeolicus FHSM VP-14840), whereas in mature individuals, the rostrum is rounded and distinctly knobbed (B; T. proriger FMNH P15144) and the foramina are either small (D; T. nepaeolicus FHSM VP-7262) or both small and large (E; T. proriger FHSM VP-3). The photographs of FMNH P15144 and FHSM VP-14040 have been inverted to face left; FHSM VP-14840 was originally identified as T. kansasensis; specimen photographs are not to scale.