2013/02/27 by Leif Tapanila, Jesse Pruitt, Alan Pradel +4 · 5 citations
Environmental Science · Earth and Planetary Sciences · #Ichthyology and Marine Biology #Paleontology and Evolutionary Biology #Fish biology, ecology, and behavior
paper · pdf · doi:10.1098/rsbl.2013.0057
openalex publication_date 2013/02/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/08
New CT scans of the spiral-tooth fossil, Helicoprion, resolve a longstanding mystery concerning the form and phylogeny of this ancient cartilaginous fish. We present the first three-dimensional images that show the tooth whorl occupying the entire mandibular arch, and which is supported along the midline of the lower jaw. Several characters of the upper jaw show that it articulated with the neurocranium in two places and that the hyomandibula was not part of the jaw suspension. These features identify Helicoprion as a member of the stem holocephalan group Euchondrocephali. Our reconstruction illustrates novel adaptations, such as lateral cartilage to buttress the tooth whorl, which accommodated the unusual trait of continuous addition and retention of teeth in a predatory chondrichthyan. Helicoprion exemplifies the climax of stem holocephalan diversification and body size in Late Palaeozoic seas, a role dominated today by sharks and rays.