Lepisosteidae Cuvier 1825

Lepisosteidae gen. et sp. indet. Fig. 23A–H Material examined UNITED STATES OF AMERICA – Mississippi • 109 isolated teeth; Catahoula Formation; MMNS VP-7685 (7 teeth), SC 2013.28.627 to28.629, SC 2013.28.630 (Fig. 23G–H), SC 2013.28.631, SC 2013.28.632, SC 2013.28.633 (9 teeth), SC 2013.28.634 (25 teeth), SC 2013.28.635 (12 teeth), SC 2013.28.636 (15 teeth), SC 2013.28.637 (12 teeth), SC 2013.28.638 (19 teeth), SC 2013.28.639 to 28.642 • 64 isolated scales; Catahoula Formation; SC 2013.28.609 to 28.617, SC 2013.28.618 (Fig. 23A–C), SC 2013.28.619 (Fig. 23D–F), SC 2013.28.620 to 28.622, SC 2013.28.623 (2 specimens), SC 2013.28.624 (2 specimens), SC 2013.28.625 (4 specimens), SC 2013.28.626 (42 specimens). Description Numerous isolated teeth are included in our Lepisosteidae sample. These teeth vary in size and overall height, but all consist of a cylindrical base and enameloid crown (Fig. 23G). In anterior/posterior view, teeth are straight to slightly lingually curved. The basal portion of the tooth is striated, and the basal outline is circular with a deep pulp cavity (Fig. 23H). The crown is formed of translucent enameloid having smooth exterior surfaces. The crown shape of large teeth varies from short and conical to slightly antero-posteriorly compressed, and those with conical crowns lack cutting edges, whereas compressed specimens are bicarinate with smooth labio-lingually oriented cutting edges. Small specimens exhibit a taller, needle-like crown that is conspicuously antero-posteriorly compressed. The crowns of these teeth exhibit sharp and elongated anterior and posterior cutting edges that do not reach the tooth base. Two scale morphologies have been identified, both of which are generally rhomboidal in outline but may also be somewhat teardrop-shaped. The external surface may or may not have a thick ganoine covering. Those with ganoine may have a smooth texture (Fig. 23A), but specimens with deeply pitted ganoine or ganoine with highly irregular margins occur (Fig. 23F). The inner surface is smooth (Fig. 23C–D) and often convex (Fig. 23B, E). A posterior projection from the main body of the scale varies from short to very elongated. Some specimens exhibit concentric growth lines on the external surface. Remarks Of the teeth in our sample, large specimens are comparable to those occurring in furrows along the maxillae and dentaries of extant Lepisosteus osseus (Linnaeus, 1758) specimens that we examined (MSC 42585, MSC 49487). The small, more needle-like specimens in our sample are similar to teeth we observed along the labial jaw margins of those L. osseus specimens. The largest scales in our sample (i.e., SC 2013.28.619) have pitted ganoine or ganoine with irregular outlines and are reminiscent of scales referred to Atractosteus. Although Grande (2010) identified four Paleogene gar taxa, he indicated that isolated teeth and scales lacked taxonomically significant features allowing for identification beyond the family level. In lieu of cranial material, we follow Ebersole et al. (2019) and refrain from assigning the Catahoula Formation gar material to any particular genus. Additionally, we cannot be certain whether differences in scale morphology within our sample represent inter- or intraspecific variation (among species versus along the body of an individual fish). Gar fossils have been documented from Eocene strata within the Gulf Coastal Plain (i.e., Breard & Stringer 1999; Westgate 2001; Ebersole et al. 2019), but none have been previously reported from the Oligocene.