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Université de Fribourg

A revision of Ophidiaster davidsoni de Loriol and Pellat 1874 from the Tithonian of Boulogne (France) and its transfer from the Valvatacea to the new forcipulatacean genus Psammaster gen. nov.

Fau, Marine ; Villier, Loïc ; Ewin, Timothy A. M. ; Gale, Andrew S.

In: Fossil Record, 2020, vol. 23, no. 2, p. 141–149

Forcipulatacea is one of the three major groups of extant sea stars (Asteroidea: Echinodermata), composed of 400 extant species, but only known from fewer than 25 fossil species. Despite unequivocal members being recognized in the early Jurassic, the evolutionary history of this group is still the subject of debate. Thus, the identification of any new fossil representatives is significant. We...

Université de Fribourg

Inference of natural selection from ancient DNA

Dehasque, Marianne ; Ávila‐Arcos, María C. ; Díez‐del‐Molino, David ; Fumagalli, Matteo ; Guschanski, Katerina ; Lorenzen, Eline D. ; Malaspinas, Anna‐Sapfo ; Marques‐Bonet, Tomas ; Martin, Michael D. ; Murray, Gemma G. R. ; Papadopulos, Alexander S. T. ; Therkildsen, Nina Overgaard ; Wegmann, Daniel ; Dalén, Love ; Foote, Andrew D.

In: Evolution Letters, 2020, vol. 4, no. 2, p. 94–108

Evolutionary processes, including selection, can be indirectly inferred based on patterns of genomic variation among contemporary populations or species. However, this often requires unrealistic assumptions of ancestral demography and selective regimes. Sequencing ancient DNA from temporally spaced samples can inform about past selection processes, as time series data allow direct...

Université de Fribourg

Ancient mitogenomics clarifies radiation of extinct Mascarene giant tortoises ( Cylindraspis spp.)

Kehlmaier, Christian ; Graciá, Eva ; Campbell, Patrick D. ; Hofmeyr, Margaretha D. ; Schweiger, Silke ; Martínez-Silvestre, Albert ; Joyce, Walter G. ; Fritz, Uwe

In: Scientific Reports, 2019, vol. 9, no. 1, p. 1-7

The five extinct giant tortoises of the genus Cylindraspis belong to the most iconic species of the enigmatic fauna of the Mascarene Islands that went largely extinct after the discovery of the islands. To resolve the phylogeny and biogeography of Cylindraspis, we analysed a data set of 45 mitogenomes that includes all lineages of extant tortoises and eight near-complete sequences of all...

Université de Fribourg

A large impact crater beneath Hiawatha Glacier in northwest Greenland

Kjær, Kurt H. ; Larsen, Nicolaj K. ; Binder, Tobias ; Bjørk, Anders A. ; Eisen, Olaf ; Fahnestock, Mark A. ; Funder, Svend ; Garde, Adam A. ; Haack, Henning ; Helm, Veit ; Houmark-Nielsen, Michael ; Kjeldsen, Kristian K. ; Khan, Shfaqat A. ; Machguth, Horst ; McDonald, Iain ; Morlighem, Mathieu ; Mouginot, Jérémie ; Paden, John D. ; Waight, Tod E. ; Weikusat, Christian ; Willerslev, Eske ; MacGregor, Joseph A.

In: Science Advances, 2018, vol. 4, no. 11, p. eaar8173

We report the discovery of a large impact crater beneath Hiawatha Glacier in northwest Greenland. From airborne radar surveys, we identify a 31-kilometer-wide, circular bedrock depression beneath up to a kilometer of ice. This depression has an elevated rim that cross-cuts tributary subglacial channels and a subdued central uplift that appears to be actively eroding. From ground...