Unexpected resilience of species with temperature-dependent sex determination at the Cretaceous–Palaeogene boundary

Abstract

It has been suggested that climate change at the Cretaceous–Palaeogene (K–Pg) boundary, initiated by a bolide impact or volcanic eruptions, caused species with temperature-dependent sex determination (TSD), including dinosaurs, to go extinct because of a skewed sex ratio towards all males. To test this hypothesis, the sex-determining mechanisms (SDMs) of Cretaceous tetrapods of the Hell Creek Formation (Montana, USA) were inferred using parsimony optimizations of SDMs on a tree, including Hell Creek species and their extant relatives. Although the SDMs of non-avian dinosaurs could not be inferred, we were able to determine the SDMs of 62 species; 46 had genotypic sex determination (GSD) and 16 had TSD. The TSD hypothesis for extinctions performed poorly, predicting between 32 and 34 per cent of survivals and extinctions. Most surprisingly, of the 16 species with TSD, 14 of them survived into the Early Palaeocene. In contrast, 61 per cent of species with GSD went extinct. Possible explanations include minimal climate change at the K–Pg, or if climate change did occur, TSD species that survived had egg-laying behaviour that prevented the skewing of sex ratios, or had a sex ratio skewed towards female rather than male preponderance. Application of molecular clocks may allow the SDMs of non-avian dinosaurs to be inferred, which would be an important test of the pattern discovered here.

Sex determination, longevity, and the birth and death of reptilian species

“…However, TSD families appeared to have suffered lower extinction rates than GSD lineages during the climate change of the Cretaceous/Palaeogene transition (Silber et al. ; Escobedo‐Galvan and Gonzalez‐Salazar ). This observation suggests that TSD taxa may have been better adapted to past climate change than GSD taxa due to their phenotypic plasticity (Kallimanis ; Escobedo‐Galvan et al.…”

Evaluating the Significance of Paleophylogeographic Species Distribution Models in Reconstructing Quaternary Range-Shifts of Nearctic Chelonians

“…Recently, there is a considerable debate about how the impact of human-induced climate changes might affect species with TSD [132]–[133], and some studies underline that climate change might jeopardize sex ratios and therefore cause severe population decline and extinction [134]. On the other hand, Silber et al [135] provided evidence that a higher proportion of TSD species compared with GSD species may have survived historic climate fluctuations suggesting some advantages of TSD over GSD, wherein Valenzuela & Adams [136] provided evidence that chelonians might have adapted to prehistoric climate change by shifting from TSD to GSD. These results suggest that the species' niches may be much more flexible than previously assumed.…”

Integrating developmental biology and the fossil record of reptiles

“…Extant Phylogenetic Bracketing does not give an answer to this problem because birds and crocodylians -the closest extant relatives of non-avian dinosaurs -have different types of sex-determining mechanisms (e.g. Silber et al, 2011). However, discovery of neosauropod nesting site at hydrothermal environment, where dinosaurs nested repetitively (Grellet-Tinner and Fiorelli 2010), suggests that TSD is unlikely in these animals.…”