Revision of the scombroid fishes from the Cenozoic of England

Abstract

Since 1966, when the last major work on fossil scombroid fishes (Scombroidei, Perciformes) from England appeared, our knowledge of the taxonomy and systematics of Recent scombroids has been thoroughly updated, improved and studied in the context of cladistic methods. In comparison, our knowledge of the fossil taxa has lagged much behind. As part of a revision of all fossil and Recent scombroid fishes, the present paper describes an updated systematic palaeontology of the English fossil taxa. These are a subset of taxa subject to a cladistic analysis of Recent and fossil genera combined, the results of which will appear in future papers. Three new genera are erected, two species transferred to other, already existing, ones and a new species is described (in a new genus). The author follows the opinion that Eothynnus Woodward, 1901 is a carangid. Several individual specimens are re-identified. The systematic affinities of Tamesichthys Casier, 1966, Eocoelopoma Woodward, 1901, Scombramphodon Woodward, 1901, Sphyraenodus Agassiz, 1844, Wetherellus Casier, 1966 and Woodwardella Casier, 1966, and a few new taxa, are here considered unknown. Aglyptorhynchus Casier, 1966 is probably a billfish, and Cylindracanthus Leidy, 1856, is possibly one as well, even though there are serious objections to this.

The one that got away from Smith Woodward: cranial anatomy of Micrornatus (Acanthomorpha: Scombridae) revealed using computed microtomography

“…The frontals surround an opening along the dorsal midline near the rear of the orbit. This opening is subtriangular and narrows posteriorly, and has been interpreted previously as a pineal foramen (Monsch 2005). However, remnants of thin bony laminae are apparent within it, both through visual inspection and in tomographs.…”

“…Among these materials was a diversity of forms currently aligned with scombroids (Monsch 2005), a group that has undergone considerable taxonomic restructuring over the past century (e.g. Regan 1909;Gosline 1968;Collette et al 1984Collette et al , 2001Johnson 1986;Carpenter et al 1995;Orrell et al 2006;Yagishita et al 2009;Betancur-R et al 2013;Miya et al 2013;Near et al 2013) but includes a core membership of three percomorph families: Scombridae (tunas and mackerels), Gempylidae (snake mackerels) and Trichiuridae (cutlassfishes).…”

“…This fossil was first described by Casier (1966) in his monumental overview of the London Clay fish fauna, where he placed it as a new species in Smith Woodward's Eocoelopoma: Eoceolopoma hopwoodi. On the basis of differences related to cranial ornament, dental morphology and patterns of skull roofing bones, Monsch (2005) recognized this individual as distinct from other species of Eocoelopoma, and erected the genus Micrornatus to accommodate it. At present, NHMUK PV OR 36136 represents the type and only example of Micrornatus.…”

The English Chalk and London Clay: two remarkable British bony fish Lagerstätten

“…Subsequent revisions to the actinopterygian body fossil record have been limited. The most substantive accounts based on historical material available to Smith Woodward and Casier include: redescriptions of the osteoglossomorph Brychaetus (Roelling 1974;Taverne 1974Taverne , 1979, accompanied by its temporary synonymization with Phaerodus (Li 1994;Li et al 1997) followed by reinstatement (Taverne 2009); revised anatomical accounts of elopiform and 'albuliform' elopomorphs (Forey 1973); redescription of the sparid Sciaenurus and placement relative to modern forms (Day 2003); and a substantial revision of scombroids and xiphioids (Monsch 2000(Monsch , 2005.…”

“…Explicit phylogenetic interpretations of fossils will yield not only an improved picture of the London Clay fauna itself, but also new potential calibrations for molecular clock analysis. This is particularly well illustrated by the diverse scombroids of the London Clay (Casier 1966;Monsch 2005), none of which have ever been formally placed within a published phylogeny. Further palaeontological constraints would particularly benefit study of this clade, with current estimates of the evolutionary timescale for tunas, mackerels and their kin differing by tens of millions of years (Miya et al 2013;Near et al 2013;Santini et al 2013).…”