Journal cover Journal topic
Fossil Record A palaeontological open-access journal of the Museum für Naturkunde
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.345 IF 1.345
  • IF 5-year value: 1.351 IF 5-year
    1.351
  • CiteScore value: 1.3 CiteScore
    1.3
  • SNIP value: 0.702 SNIP 0.702
  • SJR value: 0.442 SJR 0.442
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 17 Scimago H
    index 17
Volume 14, issue 2
Foss. Rec., 14, 129–140, 2011
https://doi.org/10.1002/mmng.201100003
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Foss. Rec., 14, 129–140, 2011
https://doi.org/10.1002/mmng.201100003
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

  01 Aug 2011

01 Aug 2011

Morphology of the anterior vertebral region in elasmobranchs: special focus, Squatiniformes

K. M. Claeson1,* and A. Hilger2 K. M. Claeson and A. Hilger
  • 1The University of Texas at Austin, Texas, USA
  • 2Helmholtz-Zentrum Berlin, Glienicker Str. 100, 14109 Berlin, Germany
  • *current address: 228 Irvine Hall, Department of Biomedical Sciences, Ohio University College of Osteopathic Medicine, Athens, OH 45701, USA

Abstract. The morphology of extant and extinct Squatiniformes is well conserved within this lineage, but differences are of consequence to character interpretations for phylogenetic analyses. Investigation of the extinct taxon †Pseudorhina alifera (Münster, 1842) from the Late Jurassic of Solnhofen with extant species of Squatina provide new evidence that members of Squatiniformes possess a basioccipital fovea. Presence of a basioccipital fovea is the ancestral condition in Neoselachians and hypothesized to be lost in members of Hypnosqualea. In addition, species of Squatina all posses a reduced occipital hemicentrum while the occipital hemicentrum in †Pseudorhina is unreduced, indicating the condition in Squatina is an example of postdisplacement heterochrony. Pristiophoriformes and Batoidea also are characterized by a lack of a basioccipital fovea and hemicentrum. However, extinct members of Batoidea, such as †Spathobatis, and modern taxa do possess a distinct notch in the posterior basicranium ventral to the foramen magnum. Except for the lack of an associated occipital hemicentrum, this notch is similar to the basioccipital fovea, but its homology is not yet addressed. Furthermore, within all species of Squatiniformes and Pristiophoriformes, as well as some members of Orectolobiformes and Carcharhiniformes, basiventral cartilages are laterally expanded, contributing to a broad articulation with the occipital condyle. The disparate taxa with modifications to the basiventral cartilages suggest a significant functional, rather than phylogenetic, signal for this feature.

doi:10.1002/mmng.201100003

Publications Copernicus
Download
Citation