[dinosaur] Romanian multituberculate + marsupial evolution limits + Middle Triassic marine coprolites + earliest tetrapod environments

Ben Creisler

Some recent non-dino papers:

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)

doi:10.1016/j.crpv.2016.04.002

http://www.sciencedirect.com/science/article/pii/S163106831630029X

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.

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Free pdf:

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)

doi:10.1093/icb/icw039

http://icb.oxfordjournals.org/content/early/2016/04/28/icb.icw039.abstract

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.

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Mao Luo, Shixue Hu, Michael J. Benton, G.R. Shi, Laishi Zhao, Jinyuan Huang, Haijun Song, Wen Wen, Qiyue Zhang, Yuheng Fang, Yuangeng Huang & Zhong-Qiang Chen (2016)

Taphonomy and palaeobiology of early Middle Triassic coprolites from the Luoping biota, southwest China: Implications for reconstruction of fossil food webs.

Palaeogeography, Palaeoclimatology, Palaeoecology

doi:10.1016/j.palaeo.2016.06.001

http://www.sciencedirect.com/science/article/pii/S0031018216301936

Abundant, exceptionally preserved coprolites are documented from the Luoping biota (Anisian, Middle Triassic) of Yunnan Province, southwest China. These coprolites can be categorized into four morphological types: A) bead to ribbon-shaped, B) short to long cylindrical-shaped, C) flattened, disk-like, and D) segmented faeces. Detailed multi-disciplinary studies reveal that coprolite type A was likely produced by invertebrate animals, while coprolite types B to D could be faeces generated by carnivorous fishes or marine reptiles, perhaps from different taxonomic groups. When compared with coprolites reported from the Lower Triassic, the Luoping forms indicate more complicated predation-prey food web networks. These evidences, combined with body fossil discoveries from Luoping, suggest the emergence of complex trophic ecosystems in the Anisian, marking the full biotic recovery following the Permian–Triassic Mass Extinction.

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Timothy I. Kearsey, Carys E. Bennett, David Millward, Sarah J. Davies, Charles J.B. Gowing, Simon J. Kemp, Melanie J. Leng, John E.A. Marshall & Michael A.E. Browne (2016)

The terrestrial landscapes of tetrapod evolution in earliest Carboniferous seasonal wetlands of SE Scotland.

Palaeogeography, Palaeoclimatology, Palaeoecology

doi:10.1016/j.palaeo.2016.05.033

http://www.sciencedirect.com/science/article/pii/S0031018216301729

Highlights

Paleosols of Tournaisian tetrapod-bearing strata in Scotland are described.

Four pedotypes identified: Entisols, Inseptisols, gleyed Inseptisols, Vertisols.

Coastal floodplain with diverse mosaic of habitats include marsh and forest.

Tetrapods lived in tropical seasonal wetland with rainfall of 1000–1500 mm/year.

Increased terrestriality in tetrapods may be driven by move to seasonal wetlands.

Abstract

The Lower Mississippian (Tournaisian) Ballagan Formation in SE Scotland yields tetrapod fossils that provide fresh insights into the critical period when these animals first moved onto land. The key to understanding the palaeoenvironments where they lived is a detailed analysis of the sedimentary architecture of this formation, one of the thickest and most completely documented examples of a coastal floodplain and marginal marine succession from this important transitional time anywhere in the world. Palaeosols are abundant, providing a unique insight into the early Carboniferous habitats and climate.

More than 200 separate palaeosols are described from three sections through the formation. The palaeosols range in thickness from 0.02 to 1.85 m and are diverse: most are Entisols and Inceptisols (63%), indicating relatively brief periods of soil development. Gleyed Inseptisols and Vertisols are less common (37%). Vertisols are the thickest palaeosols (up to 185 cm) in the Ballagan Formation and have common vertic cracks. Roots are abundant through all the palaeosols, from shallow mats and thin hair-like traces to sporadic thicker root traces typical of arborescent lycopods.

Geochemical, isotope and clay mineralogical analyses of the palaeosols indicate a range in soil alkalinity and amount of water logging. Estimates of mean annual rainfall from palaeosol compositions are 1000 –1500 mm per year. The high mean annual rainfall and variable soil alkalinities contrast markedly with dry periods that developed deep penetrating cracks and evaporite deposits. It is concluded that during the early Carboniferous, this region experienced a sharply contrasting seasonal climate and that the floodplain hosted a mosaic of closely juxtaposed but distinct habitats in which the tetrapods lived. The diversification of coastal floodplain environments identified here may link to the evolution and movement of tetrapods into the terrestrial realm.

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Free pdf:

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)

doi:10.1038/srep27259

http://www.nature.com/articles/srep27259

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.