A small Cheirolepis gets a new face

The skull of the basal ray-fin fish,
Cherolepis (Agassiz 1835a, b; Figs. 1–4), was restored/reconstructed to perfection by Pearson and Westoll 1979 (Fig. 1). I pulled scores from that data with high confidence. Everyone who is into fish uses those images. It’s a landmark study on a key taxon.

Giles et al. 2015 wrote,
“As the sister lineage of all other actinopterygians, the Middle to Late Devonian (Eifelian–Frasnian) Cheirolepis occupies a pivotal position in vertebrate phylogeny.”

Cheirolepis nested
in the large reptile tree (LRT, 1487 taxa; Fig. 5) with high Bootstrap scores, but several autapomorphic traits (= unique traits that do not blend well with sister taxa) showed  up prompting the need to go back to the fossil itself (Fig. 2).

Using DGS methods
I traced the NMS.1956.19 specimen of Cheirolepis (Figs. 2) and graphically slid the bones back to their invivo positions (Fig. 3). This technique avoids the pitfalls that attend freehand drawing, as in Pearson and Westoll 1979. Try as I might, I was not able to confirm the boxy profile that Pearson and Westoll provided to Cheirolepis (Figs. 1, 4).

Moreover
the new scores entered into the LRT proved to be much more gradual, blending in with sister taxa. The traditional lobe-fins, Onychodus and Strunius, are more primitive. The  ray-fin fish, Amia (Fig. 6), and spiny sharks, like Brachyacanthus are more derived (Fig. 5).

The NMS specimen
is much smaller than the Pearson and Westoll reconstruction (Fig. 4) and could represent variation within the genus. Certainly the spiny sharks, with an extremely large eye and short rostrum, have a facial profile more like the larger specimen than the smaller specimen, which more closely resembles the bowfin, Amia.

Shortly,
I will be assembling images of a scaled evolutionary series of taxa that document a gradual accumulation of traits at every node, now that a sufficient number of gaps are being filled by taxon inclusion. As usual, it will tradition to a large extent, but certain untested relationships are going to show.

References
Agassiz JLR 1835a. Recherches sur les Poissons fossiles, 5 volumes. Imprimerie de Petitpierre et Prince, Neuchaatel, 1420 pp.
Agassiz JLR 1835b. On the fossil fishes of Scotland. Report of the British Association for the Advancement of Science, British Association for the Advancement of Science, Edinburgh.
Giles S, et al. (6 co-authors) 2015. Endoskeletal structure in Cheirolepis (Osteichthys, Actinopterygii), an early ray-finned fish. Palaeontology 58(5):849–870.
Pearson DM and Westoll TS 1979. The Devonian actinopterygian Cheirolepis Agassiz. Earth and Environmental Science Transactions of The Royal Society of Edinburgh. 70(13-14):337–399.

wiki/Cheirolepis