Mechanisms of dermal bone repair after predatory attack in the giant stem‐group teleost Leedsichthys problematicus Woodward, 1889a (Pachycormiformes)

Abstract

Woodward, 1889a a member of the Mesozoic stem-teleost group Pachycormiformes, is the largest known ray-finned fish of all time (Actinopterygii;Ferrón et al., 2018). Pachycormiformes comprise several large suspension-feeding ray-finned fishes (Actinopterygii),

Fossil marine vertebrates (Chondrichthyes, Actinopterygii, Reptilia) from the Upper Cretaceous of Akkermanovka (Orenburg Oblast, Southern Urals, Russia)

“…A cooling of the surface waters was hypothesized in the area of the modern Northern Atlantic, especially at a palaeolatitude ranging between 30° and 60° N throughout the Late Cretaceous ( Ladant et al, 2020 ). Although water temperature fluctuations can strongly influence the spatial distribution of marine faunas ( Maduna et al, 2020 ; Amadori et al, 2022 ), a lower water temperature at higher latitudes across Santonian–Campanian sea-ways might not have been insuperable for taxa that are interpreted to be (regional) endothermic, like pachycormiform fishes (see Johanson et al, 2022 ), some lamniform sharks (see Ferrón, 2017 ), as well as plesiosaurs and mosasaurs (see Leuzinger et al, 2023 ). Moreover, lower water temperatures at higher latitudes for Santonian–Campanian seaways between North America and Europe could have been partially mitigated by the warm “proto-Gulf stream”, which was running along the surface waters from the Gulf of Mexico towards northwestern Europe during the Late Cretaceous ( Linnert et al, 2011 ; Wilmsen et al, 2021 ).…”

The Diet of Metriorhynchus (Thalattosuchia, Metriorhynchidae): Additional Discoveries and Paleoecological Implications

“…Liston [17] reviewed considerations of the paleoecology of this animal as a suspension feeder, also discussing the degree to which it was a detritivore as indicated by feeding traces [14], which has been supported by recent discoveries of pedomorphically delayed crushing maxillary dentition emerging in the largest adult individuals [20]. There have been specimens of Leedsichthys that display signs of callus bone regrowth following the attack of would-be predators, including pliosaurs [21,22]. However, a metriorhynchid tooth embedded in a Leedsichthys bone that was previously interpreted as showing signs of bone regrowth [23] was found to have resulted from a misinterpretation of a finely disrupted periosteal surface at the point of tooth puncture.…”

A New Large †Pachycormiform (Teleosteomorpha: †Pachycormiformes) from the Lower Jurassic of Germany, with Affinities to the Suspension-Feeding Clade, and Comments on the Gastrointestinal Anatomy of Pachycormid Fishes

“…A recent renaissance of interest in pachycormid research over the last few decades has made progressive steps toward resolving some of these issues, with many historic genera now better defined and several new taxa formally described [5,6,[13][14][15][16][17]. Nonetheless, the majority of these studies have focused on stratigraphically younger pachycormids, ranging from the Middle Jurassic to Late Cretaceous [5,6,[13][14][15][17][18][19][20][21], with little research attention directed towards Early Jurassic taxa [1,[22][23][24]. Early Jurassic pachycormid research has unfortunately been heavily biased towards the type taxon Pachycormus macropterus (de Blainville, 1818 [25]) [1,22,23,[26][27][28], with very few other Early Jurassic taxa receiving detailed study (see Reference [16] for †Ohmdenia and Reference [24] for †Saurostomus).…”

“…Fringing fulcra are absent in the caudal fins of Asthenocormus titanius [1,63], Martillichthys (see Supplementary File S1 for a description of the caudal fin and Figure S2), and likely also in Leedsichthys problematicus [18,21,91], suggesting that their absence might be a hitherto undetected synapomorphy of the suspension-feeding clade. However, the caudal fin is either unknown or poorly preserved in most edentulous taxa.…”