Logan King Postdoctoral researcher at Institute of Vertebrate Paleontology and Paleoanthropology, China.
Can you tell us a bit about yourself and your research interests?
My current work focuses on the soft anatomy that is found on the inside of the braincase – otherwise known as the cranial endocast, or endocast for short. More broadly, I am interested to see how the anatomy and morphology of archosaur endocasts change over long and short timespans both evolutionarily and throughout ontogeny, respectively. I specifically chose archosaurs as my preferred (but not only!) research taxa as they display an amazing amount of variability across time and throughout their lives. And considering that the most famous archosaurs, the non-avian dinosaurs, have drawn so much attention since their formal discovery, the clade also has an enormous research history to compare against.
What first interested you in this field of research?
Coming from a geology-dominant background, I have always been interested in pulling biological data from fossils. While anatomical details abound in osteology, I wanted to look more closely at soft tissues in the skull and, in particular, the brain. How do non-avian dinosaurs bridge the neuroanatomical gap between birds and non-avian archosaurs? How do we assess the different sensory abilities and cognitive functions that define non-avian dinosaurs? Can we neuroanatomically define non-avian dinosaurs when endocrania from all of Archosauria are considered? It is questions like these that really help to bring fossils taxa to life again for me and are what got me interested – and continue to drive me – in archosaur palaeoneurology.
Can you briefly explain the research you presented at SVPCA 2024?
The research I presented at SVPCA 2024 was an abbreviated version of the work recently published by myself and coauthors in Nature Communications. In our research, we demonstrated three important facets of non-avian dinosaur endocranial growth via 3D morphometrics. First, we found that endocranial specimens from both ornithischian and saurischian dinosaur taxa shared similar allometric trajectories throughout life. Secondly, we demonstrated that the juvenile-most specimens of non-avian dinosaurs sampled in our study were, morphometrically, more crown avian-like than adult non-avian dinosaurs and alligators – regardless of the juvenile specimens’ taxonomic affinity. Lastly, we compared the shape and allometric development of non-avian dinosaurs and confirmed that there was a paedomorphic link between the crown avian and non-avian dinosaur endocranial form; though this paedomorphic link was a stepwise acquisition and not accrued in a neat, linear pattern.
How will you continue to build on this research?
While the results of this work are exciting and have many implications for the neuroanatomical evolution of non-avian dinosaurs and the development of the ‘bird brain’, there is still much work to be done. For example, I have noticed how weak the modern ontogenetic sampling is for extant archosaurs. My next steps – in between finding more permanent employment – will be to increase the sample size of extant archosaur endocranial models. Without context, fossils are just really cool shaped rocks – and ‘context’ does not just mean geological or locality metadata! If we do not have a good, modern framework to fit a clade like Archosauria into, we are not really getting as much information out of the fossil record as we could be. Knowing this, I will be moving ahead with constructing an expanded dataset of modern ontogenetic series of crown archosaur ‘brains’ that can significantly increase the utility of endocranial models from extinct archosaur taxa in the future.
Jacob Quinn Honorary Research Associate at the University of Bristol, UK.
Can you tell us a bit about yourself and your research interests?
I am currently an Honorary Research Associate at the University of Bristol researching a continuation of my work as former MSc student at the university. My current focus is largely on the palaeoecology of the British Late Triassic, with a specific focus on coelacanths and other Actinopterygian fishes. I am also working with several colleagues on an exciting project into the stratigraphy and palaeoecology of a largely understudied Middle Jurassic formation in the UK that is rich in vertebrate fossils.
What first interested you in this field of research?
My interest in palaeontology began at a young age when collecting marine vertebrate fossils from the Middle Jurassic Kellaways Formation and Oxford Clay Formation that was exposed in gravel quarries around where I grew up. The taxonomic diversity of the Oxford Clay was inspiring, with organisms from all trophic levels preserved with exquisite detail. I am still greatly interested in marine vertebrates, however my focus has shifted back some 40 million years to the latest Triassic. The late Triassic is an incredibly enticing point in Earth’s history to study, with many clades of tetrapods (amongst other fauna) that were prevalent, but now decline at that time. The British Late Triassic (Rhaetian) is interesting as there has been extensive work on the micro-vertebrate faunas found in the deposits, however the macro-vertebrate fauna has been poorly studied, or largely disregarded. Understanding these latest possible Triassic records of marine vertebrates from the Rhaetian is important in documenting their extinction and the Triassic–Jurassic turnover.
Can you briefly explain the research you presented at SVPCA 2024?
The work I presented was from my MSc in palaeobiology at the University of Bristol that was recently published in the Journal of Vertebrate palaeontology. The work focused on an enigmatic Late Triassic marine reptile called Pachystropheus rhaeticus, and was done in collaboration with colleagues from the Bristol City Museum, Natural History Museum (UK), and University of Southampton. The reptile is contentious having been classified Pachystropheus as a choristodere (= champsosaur), shifting the origin date of this small clade of Middle Jurassic to Miocene aquatic, superficially crocodile-like predators. Others suggested that Pachystropheus is a thalattosaur, a group prevalent throughout the Mid-Late Triassic, based on several shared features in the postcranial skeleton between Pachystropheus and the thalattosaur Endennasaurus.
To test this, we restudied all available materials to identify all bones possibly referable to Pachystropheus. We scanned specimens at the University of Southampton, where there were one or more associated bones together, to see whether any more phylogenetically informative bones may have been hidden within. Further, this is the first time Pachystropheus material has been CT-scanned, allowing us to test the identities of more tenuous bones, which could be segmented from the matrix and viewed in all aspects. This enabled us reject previous dubious identifications and show that many bones described as Pachystropheus, were incorrect and that supposed elements belong to coelacanths. With our updated roster of bones, we were able to conduct a reassessment of its phylogeny using new character informative data, placing Pachystropheus as a small thalattosaur. So, having been considered as the first of the choristoderes, it is now regarded as the last of the thalattosaurs, extending their geological range to the latest Rhaetian. The study prompts further research, with the newly identified coelacanth and fish materials to be described in separate publications.
How will you continue to build on this research?
The initial identifications during my research into Pachystropheus allowed us to identity a plethora of coelacanth bones from public collections that had otherwise been forgotten thanks to being identified as from the enigmatic marine reptile. It turns out these fish are pretty common in the Westbury, leaving many traces beyond bones – if you pardon the pun! Of course, it is not only coelacanths that fell victim to the Pachystopheus waste basket, but several other taxa that I will also be describing, helping build a greater picture of the full story.