Macroevolutionary dynamics of dentition in Mesozoic birds (1 Viewer)

[Fred Ruhe]

Neil Brocklehurst & Daniel J. Field2, 2021

Macroevolutionary dynamics of dentition in Mesozoic birds reveal no long-term selection towards tooth loss

IScience in press
DOI: https://doi.org/10.1016/j.isci.2021.102243

Free pdf and Abstract: https://www.cell.com/iscience/pdf/S2589-0042(21)00211-X.pdf?_returnURL=https://linkinghub.elsevier.com/retrieve/pii/S258900422100211X?showall=true

Highlights

The evolutionary processes underlying tooth loss in Mesozoic birds is debated.
Analyses reveal no long-term selective pressure or trend towards toothlessness.
Tooth loss was likely a result of local selective pressures on individual lineages.
The transition to crown bird toothlessness occurred later than previously hypothesized

Summery

Several potential drivers of avian tooth loss have been proposed, although consensus remains elusive as fully toothless jaws arose independently numerous times among Mesozoic avialans and dinosaurs more broadly. The origin of crown bird edentulism has been discussed in terms of a broad-scale selective pressure or trend toward toothlessness, although this has never been quantitatively tested. Here, we find no evidence for models whereby iterative acquisitions of toothlessness among Mesozoic Avialae were driven by an overarching selective trend. Instead, our results support modularity among jaw regions underlying heterogeneous tooth loss patterns, and indicate a substantially later transition to complete crown bird edentulism than previously hypothesized (~ 90 MYA). We show that patterns of avialan tooth loss adhere to Dollo’s law and suggest that the exclusive survival of toothless birds to the present represents lineage-specific selective pressures, irreversibility of tooth loss, and the filter of the K–Pg mass extinction.

Enjoy,

Fred

 

[Fred Ruhe]

Figure 1. Results of state-dependent diversification analyses. A) Violin plots showing speciation rates of toothed and toothless avialan lineages through the Mesozoic inferred from FiSSE analysis. Width of violins indicates the density of speciation rate values inferred from 100 time-calibrated trees. B) Violin plots showing support for Null (no connection between diversification rates and presence/absence of teeth) and Trait-dependent (diversification rates depend on presence/absence of teeth) models inferred from HiSSE analysis. Width of the violin indicates the density of Akaike weights scores inferred from the 100 trees. Ichthyornis (toothed stem avialan) skull model modified from (Field et al. 2018), and Asteriornis (toothless crown bird) skull model modified from (Field et al. 2020).