New insights into Late Devonian vertebrates and associated fauna from the Cuche Formation (Floresta Massif, Colombia)
Journal of Vertebrate Paleontology
New vertebrate remains are reported from the Late Devonian (?Frasnian) Cuche Formation of northea... more New vertebrate remains are reported from the Late Devonian (?Frasnian) Cuche Formation of northeastern Colombia, including a new taxon of antiarch placoderm (Colombialepis villarroeli, gen. et sp. nov., previously reported as Asterolepis) and a new taxon of arthrodiran placoderm (Colombiaspis rinconensis, gen. et sp. nov.). We also report evidence of a stegotrachelid actinopterygian, a diplacanthid acanthodian (cf. Florestacanthus morenoi), a second antiarch placoderm (Bothriolepis sp.), a putative megalichthyid, and a putative tristichopterid. The absence of typical Euramerican markers, e.g., Asterolepis and Strepsodus, in this assemblage suggests that faunal interchange between Euramerica and Gondwana was less pronounced during the Frasnian–Famennian than previously thought (i.e., the Great Devonian Interchange hypothesis). Three arthropod taxa, including two families of spinicaudatan branchiopods and the eurypterid Pterygotus cf. bolivianus, are found to be associated with the reported vertebrate fauna. Pterygotus cf. bolivianus represents the first eurypterid described from Colombia and the youngest known pterygotid eurypterid, highlighting that pterygotids, which were competitors for large predatory fishes, did not go extinct during the major vertebrate radiation in the Early and Middle Devonian.
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Papers by James Lamsdell
The first specimen of S. tchepeliensis was found 600 m west of the southern outskirts of the agro-town of Tanezhitsy in Slutsk District, Minsk Region, at a depth of 578 m. It occurs in a clayey interbed with a thickness of about 2–3 cm that separates intercalations of halite (above) and sylvinite (below) of the sixth sylvinite bed, which is a part of the lower sylvinite bed of the third potassium horizon (the thirteenth lithological bench of clayey-halite substratum of the upper
saliniferous stratum). The specimen is near 6 cm long and includes fully articulated prosomal appendages (Fig. 1). Plant remains, including stalks of carbonized plants (from 0,5 to 1,5 cm long) and 2 cm long branch imprint of Adiantites sp. (Yurina A. L., pers. comm.) were also found together with the first specimen.
The second new eurypterid specimen was found at a nearby mining locality, 750 m to the west of the village of Velikiy Bykov (Slutsk District, Minsk Region), at a depth of 746 m. This specimen occurs in a clayey interbed with a thickness of about 4–6 cm that separates the third
sylvinite bed and an overlying halite bed. These beds are also part of the lower sylvinite stratum of the third potassium horizon of the thirteenth lithological bench of clayey-halite substratum of the upper saliniferous stratum. The second specimen is much larger (18 cm long) than the first
one but the appendages are not well preserved (Fig. 2). At a separate location in the same mine, 400 m south of the village of Pogost-2, a single branch of the plant Sphenopteris sp. (Yurina A. L., pers. comm.) was found at a depth of about 722 m in a clay unit interbedded within halite that are part of the lower sylvinite stratum of the third potassium horizon.
The new eurypterid material reveals additional information about the morphology of Soligorskopterus, specifically the broad metastoma with flattened posterior reminiscent to the metastoma of the Silurian stylonuroid Laurieipterus (Waterston, 1962) and the occurrence of a moveable spine posterodistally on podomere seven of appendages V and VI. All new eurypterid and plant specimens are concordant with the ages of the eurypterid specimens previously identified by authors
(Plax et al., 2018) as the Osovets Beds of the Streshin Regional Stage, the Middle Substage of the Famennian Stage, the Upper Devonian.
evidence of a stegotrachelid actinopterygian, a diplacanthid acanthodian (cf. Florestacanthus morenoi), a second antiarch placoderm (Bothriolepis sp.), a putative megalichthyid, and a putative tristichopterid. The absence of typical Euramerican markers, e.g., Asterolepis and Strepsodus, in this assemblage suggests that faunal interchange between Euramerica and Gondwana was less pronounced during the Frasnian–Famennian than previously thought (i.e., the Great Devonian Interchange hypothesis). Three arthropod taxa, including two families of spinicaudatan branchiopods and the eurypterid
Pterygotus cf. bolivianus, are found to be associated with the reported vertebrate fauna. Pterygotus cf. bolivianus represents the first eurypterid described from Colombia and the youngest known pterygotid eurypterid, highlighting that pterygotids, which were competitors for large predatory fishes, did not go extinct during the major vertebrate radiation in the Early and Middle Devonian.