Vlad Aurel Codrea, Alexandru Adrian Solomon, Márton Venczel & Thierry Smith (2016)
First mammal species identified from the Upper Cretaceous of the Rusca Montană Basin (Transylvania, Romania).
Comptes Rendus Palevol (advance online publication)
Multituberculate mammals are scarce in the Late Cretaceous of Europe, being recorded exclusively from the Maastrichtian terrestrial deposits of the Haţeg and Transylvanian basins, in Romania. Moreover, they all belong to the endemic and primitive cimolodontan family Kogaionidae. Here, we report multituberculate teeth originating from the Maastrichtian fluviatile sediments of the Rusca Montană Basin (Occidental Carpathians, Poiana Ruscă Mountains). This is the westernmost occurrence of these Cretaceous mammals in Romania. These teeth are assigned to Barbatodon oardaensis, the smallest Cretaceous kogaionid species. This study presents the first occurrence of this species outside the Metaliferi sedimentary area (southwestern Transylvania, Romania). The distribution of Romanian Maastrichtian kogaionids is also discussed.
Anjali Goswami, Marcela Randau, P. David Polly, Vera Weisbecker, C. Verity Bennett, Lionel Hautier, and Marcelo R. Sánchez-Villagra (2016)
Do Developmental Constraints and High Integration Limit the Evolution of the Marsupial Oral Apparatus?
Integrative and Comparative Biology (advance online publication)
Developmental constraints can have significant influence on the magnitude and direction of evolutionary change, and many studies have demonstrated that these effects are manifested on macroevolutionary scales. Phenotypic integration, or the strong interactions among traits, has been similarly invoked as a major influence on morphological variation, and many studies have demonstrated that trait integration changes through ontogeny, in many cases decreasing with age. Here, we unify these perspectives in a case study of the ontogeny of the mammalian cranium, focusing on a comparison between marsupials and placentals. Marsupials are born at an extremely altricial state, requiring, in most cases, the use of the forelimbs to climb to the pouch, and, in all cases, an extended period of continuous suckling, during which most of their development occurs. Previous work has shown that marsupials are less disparate in adult cranial form than are placentals, particularly in the oral apparatus, and in forelimb ontogeny and adult morphology, presumably due to functional selection pressures on these two systems during early postnatal development. Using phenotypic trajectory analysis to quantify prenatal and early postnatal cranial ontogeny in 10 species of therian mammals, we demonstrate that this pattern of limited variation is also apparent in the development of the oral apparatus of marsupials, relative to placentals, but not in the skull more generally. Combined with the observation that marsupials show extremely high integration of the oral apparatus in early postnatal ontogeny, while other cranial regions show similar levels of integration to that observed in placentals, we suggest that high integration may compound the effects of the functional constraints for continuous suckling to ultimately limit the ontogenetic and adult disparity of the marsupial oral apparatus throughout their evolutionary history.
Wei Wang, Li Lin, Xiao-Guo Xiang, Rosa del C. Ortiz, Yang Liu, Kun-Li Xiang, Sheng-Xiang Yu, Yao-Wu Xing & Zhi-Duan Chen (2016)
The rise of angiosperm-dominated herbaceous floras: Insights from Ranunculaceae.
Scientific Reports 6, Article number: 27259 (2016)
The rise of angiosperms has been regarded as a trigger for the Cretaceous revolution of terrestrial ecosystems. However, the timeframe of the rise angiosperm-dominated herbaceous floras (ADHFs) is lacking. Here, we used the buttercup family (Ranunculaceae) as a proxy to provide insights into the rise of ADHFs. An integration of phylogenetic, molecular dating, ancestral state inferring, and diversification analytical methods was used to infer the early evolutionary history of Ranunculaceae. We found that Ranunculaceae became differentiated in forests between about 108–90 Ma. Diversification rates markedly elevated during the Campanian, mainly resulted from the rapid divergence of the non-forest lineages, but did not change across the Cretaceous-Paleogene boundary. Our data for Ranunculaceae indicate that forest-dwelling ADHFs may have appeared almost simultaneously with angiosperm-dominated forests during the mid-Cretaceous, whereas non-forest ADHFs arose later, by the end of the Cretaceous terrestrial revolution. Furthermore, ADHFs were relatively unaffected by the Cretaceous-Paleogene mass extinction.