During the outgoing I collected the data and developed the methods to study the ecological structure of deep-time ecosystems (WP1). I compiled lists of species occurrences of well-preserved Permian and Triassic assemblages worldwide using fieldwork data, literature, online repositories, and museum collections. These datasets include data that are regularly ignored (i.e. incomplete specimens, microfossils, footprint) in broad diversity studies (Task 1.1). I participated in fieldwork campaigns with the Palaeobiology Group of Virginia Tech, targeting the Triassic geological formations of the southwest USA (Arizona, Texas, New Mexico). This was important to fill in a major low-latitude gap in the fossil record and collecting new data from the Middle Triassic Moenkopi Formation of Arizona. Fieldwork resulted in the creation of the first collection of Moenkopi Formation vertebrates that will be accessioned to the Utah Museum of Natural History (Task 1.2). Using these novel data, I revised the fossil record of the Middle and Late Triassic formations of the southwest USA and created a new microvertebrate collection (description in progress), a redescription of Anisodontosaurus (one of the first herbivorous reptiles following the PTME), and the creation of extensive datasets of species for following analyses.
I implemented a method that transforms occurrence data into ecological data – a necessary step to quantify metrics of ecological diversity in assemblages (WP2). Each of more than 400 species (summarising over 15000 occurrences) in over 25 assemblages was scored for five ecological traits (body size, diet, habitat, locomotion, growth). I used these data to quantify metrics of ecological significance for each assemblage (e.g. diversity, richness, disparity, and redundancy). The Triassic assemblages of the USA and South Africa were prioritised because of the availability of relevant collections and fossil species during the outgoing phase, however, future work will include additional ~40 other Permian-Triassic assemblages worldwide, for which I began collecting data.
These data were analysed using a new protocol that estimates the ecological properties of extinct assemblages and, for the first time, applies resampling strategies to account for the uneven sampling of different assemblages.
These analyses helped assess the ecological impact of the PTME (WP3). It is known that Permian ecosystems were dominated by synapsids that became only a marginal component of Triassic ecosystems, which were instead dominated by reptiles. Our work on the South Africa Karoo Basin shows that the turnover and evolution of new dominant groups also introduced new ecological roles. These were linked to new anatomical adaptations (diet, locomotion), habitat preferences and physiology (growth strategy). In other words, surviving groups occupied new distinct ecological roles rather than the recycling previously available niches. This indicates that the extinction event had a drastic impact not only on the species composition of terrestrial ecosystems but also on their ecological structure and composition and that the appearance of new ecological roles is linked to the appearance/diversification of new groups.
The patterns of recovery from the PTME were investigated at the local/regional level using the exceptional data (WP4). Thanks to the dataset assembled in WP1, I could explore the ecological recovery of ecosystems in the low-latitude Triassic succession of the southwest of the USA (Arizona, Texas, New Mexico) at unprecedented geographical and stratigraphic scales. Results show that Middle Triassic ecosystems were low-diversity and relatively unstable compared to younger assemblages. I identified a first ‘unstable’ phase of recovery, which extends until the early Late Triassic (Carnian) and is characterised by high turnover and low continuity of groups and ecological roles. Only Norian communities become more stable thanks to the diversification of crocodile-line and bird-line reptiles into new ecological modes.
The project fully achieved training and knowledge transfer objectives and milestones, including the development of research skills (data collection, fieldwork, ecological modelling, resampling, R coding), leadership skills (supervision, teaching), management, science communication, and skill exchange.
Progress and results were disseminated via: one in a peer-review publication (several in preparation), four conference attendances (two conference oral presentations, one poster and one in-person invited presentation; three outreach events; two outreach online talks, via social media and a dedicated webpage on the researcher's website.
