Pythonichthys colei ( Müller, 1999 )

Ebersole, Jun A., Cicimurri, David J. & Stringer, Gary L., 2019, Taxonomy and biostratigraphy of the elasmobranchs and bony fishes (Chondrichthyes and Osteichthyes) of the lower-to-middle Eocene (Ypresian to Bartonian) Claiborne Group in Alabama, USA, including an analysis of otoliths, European Journal of Taxonomy 585, pp. 1-274 : 187-189

Pythonichthys colei ( Müller, 1999)

Fig. 69 C–D

Eosolea texana Dante & Frizzell in Frizzell & Dante, 1965: 716 , pl. 88, figs 15, 20.

Pythonichthys sp. – Breard & Stringer 1995: 80.

“genus aff. Panturichthys ” colei – Müller 1999: 68 , pl. 20, figs 4–5.

“genus Heterenchelyidarum ” colei – Nolf & Stringer 2003: 5 , pl. 1, figs 3–8.

Material examined

UNITED STATES OF AMERICA – Alabama • 2 otoliths GLS otolith comparative collection (1 specimen), WSU CC 474.4 .

Description

Species characterized by small otoliths of 2–3 mm length, height slightly less than length (height/length ratios approximately 85–90%). Shape almost circular to slightly oval. Margins tend to be smooth. Angle along posterodorsal margin. Ventral rim regularly curved. Inner face mainly smooth, convex, with no depressed area or ventral furrow. Sulcus obvious, not deeply impressed. No clear division of ostial and caudal portions of sulcus. Sulcus primarily located medially, extends across approximately 75% of inner face. Ventral margin of sulcus may undulate, especially in posterior portion. Posterior end of sulcus mainly rounded, tapers slightly. No crista superior or crista inferior. Outer face slightly concave, mainly featureless.

Remarks

Pythonichthys colei is quite rare in the Claiborne Group formations, with only two specimens being recovered from the Lisbon Formation. This rare occurrence is not unusual, as Müller (1999) reported only 11 specimens of this species from the approximately 12 000 otoliths from the Tertiary of the US Atlantic Coastal Plain. Although Nolf & Stringer (2003) reported 90 specimens of P. colei (as “genus Heterenchelyidarum ” colei ) from 5 559 otoliths from the late Eocene Yazoo Clay, the taxon still represented less than 2% of the total assemblage. One unusual occurrence of this species is in the Clayton Formation (Paleocene) of central Arkansas, where it represents approximately 24% of the total specimens ( Stringer & Sloan 2018). This abundance is highly atypical, as, like its fossil counterparts, modern representatives of this family are rare and not well studied ( Smith et al. 2012).

Stratigraphic and geographic range in Alabama

This species was recovered only from the “upper” Lisbon Formation at site ACh-8. Bartonian, zones NP16 and NP17.

Figures

Fig. 69. Claiborne Group, “upper” Lisbon Formation, otoliths. A–B. Albula sp., MSC 562. A. Inner face (right sagitta). B. Dorsal view. — C–D. Pythonicthys colei (Müller, 1999), WSU CC 474. C. Inner face (left sagitta). D. Dorsal view. — E–F. Muraenesocidae Kaup, 1859, indet., MSC 39064. E. Inner face (left sagitta). F. Dorsal view. — G–H. Ariosoma nonsector Nolf & Stringer, 2003, MSC 39069. G. Inner face (left sagitta). H. Dorsal view. — I–J. Paraconger sector (Koken, 1888), MSC 39052. I. Inner face (right sagitta, broken on anterodorsal angle). J. Dorsal view. — K–L. Pseudophichthys sp., MSC 37059.2. K. Inner face (right sagitta). L. Dorsal view. — M–N. Rhynchoconger sp., MSC 37059.6. M. Inner face (left sagitta). N. Dorsal view. — O–P. Gnathophis meridies (Frizzell & Lamber, 1962), MSC 37059.XX. O. Inner face (right sagitta). P. Dorsal view. — Q–R. Myripristis sp., MSC 39047. Q. Inner face (right sagitta). R. Dorsal view. Scale bars: A–B =5 mm; C–R =2 mm.