Justin Reynolds’s scientific contributions

[This corrects the article DOI: 10.1371/journal.pone.0300289.].

Giant Late Triassic ichthyosaurs have been shrouded in mystery for more than two centuries. Due at large to their fragmentary fossil record, giant ichthyosaur palaeoecology, morphology and extinction are still a matter of important debate, making every new data crucial for the understanding of these past giants. We present the results of the latest studies on these marine reptiles, focusing on the morphology and bone histology of the newly described Ichthyotitan severnensis from the Rhaetian Westbury Formation of SW England (Lomax et al., 2024). Although the taxonomic assignment remains uncertain due to the incompleteness of the material, Ichthyotitan severnensis represents the first formally named giant ichthyosaur from the Rhaetian. The remains attributed to I. severnensis help us to reassess the size of ichthyosaurs in the latest Triassic, of which appears comparable to modern-day blue whales, indicating that extreme gigantism (length >25 m) evolved at least once outside of and long before Cetacea. The bone histology of I. severnensis confirms previous studies (Perillo & Sander, 2024) on the occurrence of an atypical histotype characterizing giant Late Triassic ichthyosaur lower jaws, probably linked to gigantism or to selective pressures in feeding. The case of I. severnensis highlights the crucial importance of collaboration between citizen scientists and palaeontologists for recovering new specimens, otherwise doomed to be lost. Finally, we address the need for further comparative studies with other ichthyopterigians and cetaceans to answer the many still open questions.

Giant Late Triassic ichthyosaurs have been shrouded in mystery for more than two centuries. Due at large to their fragmentary fossil record, giant ichthyosaur palaeoecology, morphology and extinction are still a matter of important debate, making every new data crucial for the understanding of these past giants. We present the results of the latest studies on these marine reptiles, focusing on the morphology and bone histology of the newly described Ichthyotitan severnensis from the Rhaetian Westbury Formation of SW England (Lomax et al., 2024). Although the taxonomic assignment remains uncertain due to the incompleteness of the material, Ichthyotitan severnensis represents the first formally named giant ichthyosaur from the Rhaetian. The remains attributed to I. severnensis help us to reassess the size of ichthyosaurs in the latest Triassic, of which appears comparable to modern-day blue whales, indicating that extreme gigantism (length >25 m) evolved at least once outside of and long before Cetacea. The bone histology of I. severnensis confirms previous studies (Perillo & Sander, 2024) on the occurrence of an atypical histotype characterizing giant Late Triassic ichthyosaur lower jaws, probably linked to gigantism or to selective pressures in feeding. The case of I. severnensis highlights the crucial importance of collaboration between citizen scientists and palaeontologists for recovering new specimens, otherwise doomed to be lost. Finally, we address the need for further comparative studies with other ichthyopterigians and cetaceans to answer the many still open questions.

Giant ichthyosaurs with body length estimates exceeding 20 m were present in the latest Triassic of the UK. Here we report on the discovery of a second surangular from the lower jaw of a giant ichthyosaur from Somerset, UK. The new find is comparable in size and morphology to a specimen from Lilstock, Somerset, described in 2018, but it is more complete and better preserved. Both finds are from the uppermost Triassic Westbury Mudstone Formation (Rhaetian), but the new specimen comes from Blue Anchor, approximately 10 km west along the coast from Lilstock. The more complete surangular would have been >2 m long, from an individual with a body length estimated at ~25 m. The identification of two specimens with the same unique morphology and from the same geologic age and geographic location warrants the erection of a new genus and species, Ichthyotitan severnensis gen. et sp. nov. Thin sections of the new specimen revealed the same histological features already observed in similar giant ichthyosaurian specimens. Our data also supports the previous suggestion of an atypical osteogenesis in the lower jaws of giant ichthyosaurs. The geological age and giant size of the specimens suggest shastasaurid affinities, but the material is too incomplete for a definitive referral. Ichthyotitan severnensis gen. et sp. nov., is the first-named giant ichthyosaur from the Rhaetian and probably represents the largest marine reptile formally described.