Wednesday, November 29, 2017

[Paleontology • 2017] The Squamation of the Eocene stem-Basilisk Geiseltaliellus maarius (Squamata: Iguanidae: Corytophaninae) from Messel, Germany


Geiseltaliellus maarius  Smith, 2009

life reconstruction by J. Eberhardt & A. Vogel  (SMF)
Smith, 2017SALAMANDRA. 53(4) 

Abstract

 An exceptional new specimen of the stem-basilisk Geiseltaliellus maarius from the middle Eocene of Messel, Germany, preserves details of the squamation of this extinct species. The dorsum and extremities were covered by small, rhomoidal scales, about 0.2 mm in size in most places; somewhat larger scales were present on the lower extremities and on the head. Scales of the venter were arranged in transverse rows, unlike in extant Polychrus and Laemanctus. There is some evidence that the scales on the extremities possessed keels, as in extant basilisks and Polychrus. Keratin appears to be preserved in places. The “Oberhäutchen” is nearly featureless, probably the result of postmortem microbial decomposition; scale organs were not observed. Overall, the body of G. maarius possessed a fine, homogeneous squamation most similar to Basiliscus. Possible sexual dimorphism in the form of the parietal crest raises the prospect of a projecting median keel composed of skin in male G. maarius, although direct evidence on this point is currently lacking. The squamation of the tail is discussed in light of the pseudoautotomy shown by this species. 

Key words: Fossils, Corytophanidae, Eocene, scales, keratin.


Figure 1. Skeleton with skin shadows of Geiseltaliellus maarius, SMF ME 11380a (part).
 (A) Detail of temple region of head. (B) Detail of throat or shoulder region. (C) Detail of right lower leg scales (over tibia and fibula). (D) Detail of left lower leg scales (torn downward and preserved around toe). (E) Detail of digit IV of left pes. Scale bar is 5 mm.

Figure 8. Reconstruction of the squamation of male Geiseltaliellus maarius from Messel.
Juliane Eberhardt (SMF) drew the life reconstruction, colored by Anika Vogel (SMF). 



 K. T. Smith. 2017. The Squamation of the Eocene stem-basilisk Geiseltaliellus maarius (Squamata: Iguanidae: Corytophaninae) from Messel, Germany. SALAMANDRA. 53(4); 519–530.  

  

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