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[dinosaur] Litopterna and Perissodactyla phylogenetic tree + juvenile glyptodont + beaver evolution (free pdfs) [+ Archaeogaia]

Ben Creisler

Some recent Cenozoic mammal papers (mostly) with free pdfs:

NicolÃs R. Chimento & Federico L. Agnolin (2020)
Phylogenetic tree of Litopterna and Perissodactyla indicates a complex early history of hoofed mammals.
Scientific Reports 10, Article number: 13280

Free pdf:

The Litopterna is an extinct clade of endemic South American ungulates that range from Paleocene up to late Pleistocene times. Because of their unique anatomy, litopterns are of uncertain phylogenetic affinities. However, some nineteenth century authors, considered litopterns as related to perissodactyl ungulates, a hypothesis recently sustained by molecular data. The aim of the present contribution is to include litopterns and other South American related taxa in a comprehensive phylogenetic analysis together with several extant and extinct basal perissodactyl ungulates. The analysis resulted in the nesting of litopterns and kin as successive stem-clades of crown Perissodactyla. Further, litopterns are not phylogenetically grouped with any North American basal ungulate, in agreement with some previous proposals. Presence of pan-perissodactyls in South America and India indicates that southern continents probably played an important role in the early evolution of hoofed mammals.



Laureano R. GonzÃlez Ruiz, Diego Brandoni, Alfredo E. Zurita, Jeremy L. Green, Nelson M. Novo, Adan A. Tauber & Marcelo F. Tejedor (2020)
Juvenile Glyptodont (Mammalia, Cingulata) from the Miocene of Patagonia, Argentina: Insights into Mandibular and Dental Characters.
Journal of Vertebrate Paleontology Article: e1768398
doi: https://doi.org/10.1080/02724634.2020.1768398

Free pdf:

The earliest complete glyptodonts (Glyptodontidae, Cingulata) found belong to the Propalaehoplophorinae from Santa Cruz Formation (late early Miocene, Burdigalian) in Patagonia, Argentina. Although several skulls and mandibles have been described from this formation, and assigned to five genera (Propalaehoplophorus Ameghino, Cochlops Ameghino, Asterostemma Ameghino, Eucinepeltus Ameghino, and Metopotoxus Ameghino), the fossil record and knowledge of juvenile specimens of glyptodonts are still poor. Here, we provide a detailed morphological description of a mandible of a juvenile propalaehoplophorinae glyptodont from the Santa Cruz Formation, using micro-computed tomography and scanning electron microscopy images. We compare the juvenile mandible with adult specimens and discuss the taxonomic assignment, the juvenile and adult mandibular and dental characters, and dental eruption and tooth wear.


Robin M. D. Beck & Matias L. Taglioretti (2020)
A Nearly Complete Juvenile Skull of the Marsupial Sparassocynus derivatus from the Pliocene of Argentina, the Affinities of "Sparassocynids", and the Diversification of Opossums (Marsupialia; Didelphimorphia; Didelphidae)
Journal of Mammalian Evolution 27: 385â417
DOI: https://doi.org/10.1007/s10914-019-09471-y
https://link.springer.com/article/10.1007/s10914-019-09471-y Â

Free pdf:


Tessa Plint, Fred J. Longstaffe, Ashley Ballantyne, Alice Telka & Natalia Rybczynski (2020)
Evolution of woodcutting behaviour in Early Pliocene beaver driven by consumption of woody plants.
Scientific Reports 10, Article number: 13111
doi: https://doi.org/10.1038/s41598-020-70164-1

Free pdf:

Modern beavers (Castor) are prolific ecosystem engineers and dramatically alter the landscape through tree harvesting and dam building. Little is known, however, about the evolutionary drivers of their woodcutting behaviour. Here we investigate if early woodcutting behaviour in Castoridae was driven by nutritional needs. We measured stable carbon and nitrogen isotopes (Î13C and Î15N) of coeval subfossil plants and beaver collagen (Dipoides sp.) from the Early Pliocene, High Arctic Beaver Pond fossil locality (Ellesmere Island), in order to reconstruct Dipoides sp. diet. Isotopic evidence indicates a diet of woody plants and freshwater macrophytes, supporting the hypothesis that this extinct semiaquatic beaver engaged in woodcutting behaviour for feeding purposes. In a phylogenetic context, the isotopic evidence implies that woodcutting and consumption of woody plants can be traced back to a small-bodied, semiaquatic Miocene castorid, suggesting that beavers have been consuming woody plants for over 20 million years. We propose that the behavioural complex (swimming, woodcutting, and consuming woody plants) preceded and facilitated the evolution of dam building. Dam building and food caching behaviours appear to be specializations for cold winter survival and may have evolved in response to late Neogene northern cooling.


Archaeogaia macachaae gen. et sp. nov.Â

Ana Natalia Zimicz, Mercedes FernÃndez, Mariano Bond, Laura Chornogubsky, Michelle Arnal, Magalà CÃrdenas & Juan Carlos Fernicola (2020)
Archaeogaia macachaae gen. et sp. nov., one of the oldest Notoungulata Roth, 1903 from the early-middle Paleocene Mealla Formation (Central Andes, Argentina) with insights into the Paleocene-Eocene south American biochronology.
Journal of South American Earth Sciences (advance online publication)
doi: https://doi.org/10.1016/j.jsames.2020.102772


A new genus and species (Archaeogaia macachaae) is described within order Notoungulata, the most diverse clade of South American native ungulates.
This new taxon comes from the upper levels of the Mealla Formation (late Danian-early Selandian, Salta Group), and constitutes the second mammalian taxa known for this unit.
Together with Simpsonotus spp., this finding constitutes the most ancient record for the order Notoungulata.
These new finding reinforces the necessity of new paleontological prospections in the Paleocene of the Northwestern Argentina, particularly in the Salta Group.


In this contribution, we report the discovery of Archaeogaia macachaae gen. et sp. nov., one of the oldest notoungulate recovered from the upper section of Mealla Formation in the Tonco Valley (Northwestern Argentina, Salta Province). The new material consists on a left mandibular fragment with damaged m1 and complete m2-3. Archaeogaia macachaae is characterized by the following combination of features: m1 slightly shorter than m2 and both larger than m3; brachydont molars; talonid mesio-distally shorter than trigonid; metaconid slightly taller than protoconid and distally placed; reduced paraconid in m2; metalophid straight in m2â3, but it runs mesially forming a slightly obtuse angle in the labial edge in m2, whereas it is more transverse in m3; transverse entolophid; mesial cingulid extending from the middle to the lingual face of molars; and distal cingulid connecting the hypoconulid with the mesial face of the entoconid on m2â3. We perform a phylogenetic analysis based on a data matrix composed of 147 craniodental characters and 70 taxa. The analysis yields 6104 most parsimonious trees of 423 steps each. In the strict consensus previously well-supported clades collapse into a polytomy; and Archaeogaia is positioned within the order Notoungulata based on two synapomorphies: a) presence of a transverse entolophid, and b) lower cheek teeth with short mesio-distal protolophid, transverse metalophid and mesio-distal hypolophid slightly convex labially. The former character was recovered as a synapomorphy for Notoungulata in several previous studies. According to the reduced consensus, Archaeogaia occupies different positions within the order; these fluctuating locations could be the result of the presence of plesiomorphic features in the holotype, and the absence of the structures that define the notoungulate clades in which the new taxon is located. The paleomagnetic data indicates that the Mealla Formation was deposited during Chron 27r to the base of Chron 26r (latest Danian-earliest Selandian). In this context, we discuss the finding of Archaeogaia, and the age of Mealla Formation in the South American biochronology.


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