Lopadichthys colwellae, Murray & Zelenitsky & Brinkman & Neuman, 2018

† LOPADICHTHYS COLWELLAE SP. NOV.

Holotype: TMP 2015.011 View Materials .0001, a complete fish preserved in left lateral view ( Fig. 7).

Paratypes: TMP 2015.011 View Materials .0004, a complete fish preserved in left lateral view ( Fig. 8), and TMP 2015.011 View Materials .0005, the posterior portion of a fish preserving the dorsal, anal and caudal fins and most of the body, but missing the head and anteroventral body, preserved in left lateral view ( Fig. 9) .

Type locality and horizon: Paskapoo Formation, Calgary, Alberta, Canada; Palaeocene in age.

Etymology: The specific epithet is in honour of Jane Colwell-Danis in recognition of her considerable contribution to vertebrate palaeontology in Alberta. She has published under the names Colwell, Danis and Colwell-Danis.

Diagnosis: A deep-bodied osteoglossomorph fish with a head depth slightly greater than head length; two heads on the hyomandibula; striations on the opercle radiating from the facet for articulation with the hyomandibula; 45–47 vertebral centra with 19–22 abdominal; anteriormost centra with numerous pits forming an open, lacy bone texture; and short deep lower jaw with the level of articulation anterior to the orbit and with a high coronoid process on the dentary. Differs from members of the suborder Osteoglossoidei (caudal formula I,7,8,I) by having a caudal formula of I,8,8,I. Further differs from subgroups within Osteoglossoidei by lacking an elongate pectoral fin ray and reticulate scales (found in many osteoglossids); having abdominal pelvic fins and unexpanded pectoral fin (unlike the anteriorly placed pelvic fins and expanded pectoral fins of Pantodon ); having a small anal fin not connected with the caudal fin (unlike the elongate anal fin confluent with the caudal fin found in notopterids); jaws terminal and unmodified (unlike the modifications of the jaws found in mormyrids). Differs from species of † Joffrichthys by having anteriormost abdominal and posterior caudal vertebral centra with many small pits and a network of bone forming a lacy structure, rather than ‘H-shaped’ (i.e. two large pits laterally separated by a strong bar of bone), and by having a relatively shorter and deeper caudal peduncle. Differs from Hiodontiformes by having a rounded dorsal border to the opercle (without the posterodorsal opercular spine as found in Hiodon and † Eohiodon ). Differs from basal osteoglossomorphs by having six rays in the pelvic fin (instead of seven rays in † Wilsonichthys , † Shuleichthys , † Xixiaichthys and hiodontiforms).

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