Search bioRxiv⌕ Search

Biology subjects

Stockdale, M. T.

Publications and source records attributed to Stockdale, M. T..

2 recordsLinked to original sources

Approaches to Species Distribution Modelling in Dinosaurs and Other Fossil Organisms

SDM describes a family of methods aiming to predict the geographic distribution of organisms using environmental data such as climate variables. It is a versatile tool in estimating ecological communities and interactions both spatially and through time. However, it has had limited utility in predicting the geographic distribution of fossil organisms. Due to preservation and sampling biases, fossil data does not satisfy the assumptions of species distribution models. Here is presented an analysis proposing a new methodology, which substitutes the conventional pseudoabsence data for fossil occurrences from non-target species. This approach eliminates variation in preservation and sampling, and returns a SDM which performs better than a conventional example. This model concludes that the ceratopsian Triceratops may have been widespread across North America, and beyond the region where its fossils have been recovered. The geographic distribution of Triceratops appears to have been governed by seasonality in temperature and temperature of the coldest month.

paleontology↗

Constraining the global niche suitability of the Eusuchia clade across the Cretaceous-Paleogene boundary.

The crocodiles and their close relatives, the alligators and gharials, have a compelling evolutionary history. They are a clade of great antiquity, with their most recent common ancestor emerging within the Mesozoic. However, unlike many groups of such a great age, the crocodilians have an extensive crown-group, with around two dozen extant examples. They have a limited ecomorphology, which has varied little since their inception, and their biogeography has been shown to interact closely with climate. The biogeography of crocodilians in deep time remains an outstanding question, which is complicated further by the limitations of the fossil record. The fossil record is fundamentally incomplete yet represents the most common method used to infer biogeography of organisms. The scarcity of fossil remains makes apparent absences difficult to confirm. Preservation bias will promote fossil occurrences in areas with a high sedimentation rate, which may not be the true ecological niche for a given taxon. This study uses species distribution models of extant crocodilians to infer the ecological niche of related taxa in the Maastrichtian and Danian. Models indicate a much wider latitudinal range than is observed among extant examples, and the invasion of new ecospace following the end-Cretaceous mass extinction. In addition, we find that while temperature is of significance to crocodilian biogeography, it is precipitation that is the most influential climatic variable.

paleontology↗