Reappraisal of Mesozoic fishes and associated invertebrates and flora from Talbragar and Koonwarra, eastern Australia

Abstract

Eastern Australia has two major Mesozoic fossil localities. The Talbragar Fish Bed in central west New South Wales contains an assemblage of Upper Jurassic fishes, plants and insects. The Koonwarra Fossil Bed, in South Gippsland, Victoria, has an assemblage of Lower Cretaceous fishes, plants and insects. The geological settings of these localities are described. Each locality has a common genus of fish that was originally described as Leptolepis. The names of both these fish have been changed, the Talbragar one to Cavenderichthys talbragarensis and the Koonwarra one to Waldmanichthys koonwarri. Both of these fish have been placed into the Family Luisiellidae, together with a Patagonian fish, Luisiella feruglioi. Each locality also has a member of the family Archaeomenidae: Archaeomene tenuis from Talbragar and Wadeichthys oxyops from Koonwarra. The relationships of these and other fish have been discussed by various authors over the last 20 years and a summary of these comments is presented, as well as a brief comparison between the plants of both localities. The localities of Talbragar, Koonwarra and the Argentinian fishes during the Mesozoic appear to have similar palaeo-environmental settings, which may explain the similarities in the assemblages. The Australian localities contain well-preserved specimens which shed light on the diversity and extent of fishes in southern Gondwana, a region otherwise poorly represented in the fossil record.

High-latitude neonate and perinate ornithopods from the mid-Cretaceous of southeastern Australia

“…The presence of diverse ectothermic tetrapods, such as squamates, turtles, and crocodylomorphs, indicates a milder climate than some of the higher-palaeolatitude sites, including the Eumeralla and Wonthaggi formations 9,29–32,86 . The Eumeralla and Wonthaggi formations were deposited within the Australian-Antarctic rift valley at a palaeolatitude of ~70°S 38,87 and were interpreted as representing wet lowlands, large braided rivers, forested floodplains, and shallow lakes 37,38 . Palaeontological, palaeobotanical, sedimentological, and isotopic data suggest cold mean annual temperatures, between –6 to +5 °C, but mean annual temperatures as high as 10 °C were also proposed 28,36,39–41 .…”

Vicariance and dispersal in southern hemisphere freshwater fish clades: a palaeontological perspective

“…†Archaeomenids and †luisiellids are poorly known freshwater stem teleost groups with a southern Gondwanan distribution (Sferco, López‐Arbarello & Báez, ; Bean, ). The age of these taxa (†Archaeomenidae: Early Jurassic–Early Cretaceous; †Luisiellidae: Late Jurassic–Early Cretaceous) is consistent with a continuous Jurassic range encompassing South America, Antarctica and Australia [but see Su, for a putative †archaeomenid from the Early Jurassic of China].…”

Otoliths in situ in the stem teleostCavenderichthys talbragarensis(Woodward, 1895), otoliths in coprolites, and isolated otoliths from the Upper Jurassic of Talbragar, New South Wales, Australia

“…The identity of the predator(s) feasting on small C. talbragarensis specimens is as yet unknown, but Bean (2017) suggested Coccolepis Agassiz, 1843, a chondrostean known from the Talbragar Fish Bed. Nevertheless, given that the numerous fish fossils in the Talbragar Fish Bed are considered to have resulted from a mass mortality event, probably caused by volcanic activity, it appears reasonable to assume that the predator producing these coprolites may not have been an aquatic animal and was perhaps benefiting from drifting dead fish in the freshwater lake after a mass mortality event.…”

“…5A-D) but also the strange triangular otoliths of unknown non-teleostean relationships described from Lower and Middle Jurassic deposits of Europe as Archaeotolithus Stolley, 1912 (Schwarzhans, 2018). It is likely that these otoliths originated from fishes of which articulated skeletons are already known from the Talbragar Fish Bed, but specimens with otoliths in situ have not yet been discovered, i.e., Coccolepis australis Woodward, 1891 (a chondrostean), Uarbryichthys latus Wade, 1941 (a macrosemiiform) (Bean, 2017), or Archaeomaene tenuis Woodward 1895, Madariscus robustus (Woodward, 1895), Aphnelepis australis Woodward, 1895, and Aetheolepis mirabilis (Woodward, 1895), originally placed in semionotids (Semionotiformes) by Woodward (1895) but later considered to be pholidophoriforms (Wade, 1941;Patterson, 1993;Arratia, 2013).…”