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1. Equus cf. livenzovensis from Montopoli, Italy (early Pleistocene; MN16b; ca. 2.6 Ma)

   https://doi.org/10.4435/BSPI.2018.13  

   Bernor, R.L. (October 2018, Bollettino della Società paleontologica italiana)

   We report here the occurrence and metric characteristics of a large species of Equus from Montopoli (Tuscany, Italy) correlated with the middle Villafranchian, 2.6 Ma (early Pleistocene). This species co-occurs with a rare “Hipparion” sp. at Montopoli. We compare the Montopoli Equus cf. livenzovensis with a large suite of extant Equus including zebras, asses and a large suite of fossil Equus using bivariate and log10 ratio analyses of anterior and posterior 1st phalanges III. Our comparisons show that Montopoli anterior and posterior 1st phalanges III are larger than in living zebras and asses and comparable in size and proportions to the early Pleistocene large Chinese species Equus eisenmannae and late Pleistocene Rancho La Brean Equus occidentale. Equus livenzovensis was a larger species than Equus stenonis and Equus stehlini. Equus cf. livenzovensis is not represented as far as we know by skulls and dentitions in the Italian Villafranchian record. 

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2. Testing Equid Body Mass Estimate Equations on Modern Zebras—With Implications to Understanding the Relationship of Body Size, Diet, and Habitats of Equus in the Pleistocene of Europe

   https://doi.org/doi:10.3389/fevo.2021.622412  

   Saarinen, J. (February 2021, Frontiers)

   null (Ed.)

   The monodactyl horses of the genus Equus originated in North America during the Pliocene, and from the beginning of the Pleistocene, they have been an essential part of the large ungulate communities of Europe, North America and Africa. Understanding how body size of Equus species evolved and varied in relation to changes in environments and diet thus forms an important part of understanding the dynamics of ungulate body size variation in relation to Pleistocene paleoenvironmental changes. Here we test previously published body mass estimation equations for the family Equidae by investigating how accurately different skeletal and dental measurements estimate the mean body mass (and body mass range) reported for extant Grevy’s zebra (Equus grevyi) and Burchell’s zebra (Equus quagga). Based on these tests and information on how frequently skeletal elements occur in the fossil record, we construct a hierarchy of best practices for the selection of body mass estimation equations in Equus. As a case study, we explore body size variation in Pleistocene European Equus paleopopulations in relation to diet and vegetation structure in their paleoenvironments. We show a relationship between diet and body size in Equus: very large-sized species tend to have more browse-dominated diets than small and medium-sized species, and paleovegetation proxies indicate on average more open and grass-rich paleoenvironments for small-sized, grazing species of Equus. When more than one species of Equus co-occur sympatrically, the larger species tend to be less abundant and have more browse-dominated diets than the smaller species. We suggest that body size variation in Pleistocene Equus was driven by a combined effect of resource quality and availability, partitioning of habitats and resources between species, and the effect of environmental openness and group size on the body size of individuals 

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3. Target Deformation of the Equus stenonis Holotype Skull: A Virtual Reconstruction

   https://doi.org/10.3389/feart.2020.00247  

   Cirilli, O. (June 2020, Frontiers)

   Pandolfi, L. (Ed.)

   Equus stenonis is one of the most prevalent European Pleistocene fossil horses. It is believed to be the possible ancestor of all Old World Early Pleistocene Equus, extant zebras and asses, and as such provides insights into Equus evolution and its biogeography and paleoecology. The Equus stenonis holotype skull (IGF560) was first described by Igino Cocchi in 1867, from the Early Pleistocene locality of Terranuova (Upper Valdarno basin, Italy). IGF560 is a nearly complete, although medio-laterally crushed and badly compressed skull. Here we provide the first application of a new virtual reconstruction protocol, termed Target Deformation, to the Equus stenonis holotype. The protocol extends beyond classic retrodeformation by using target specimens as a guide for the virtual reconstruction. The targets used as a reference are two fragmentary, yet well-preserved E. stenonis skulls, coming from Olivola (Italy; IGF11023) and Dmanisi (Georgia; Dm 5/154.3/4.A4.5), both Early Pleistocene in age. These two specimens do not display any major deformation, but preserve different, only slightly overlapping portions of the skull. The virtual reconstruction protocol we carried out has shown its feasibility, by producing two 3D models whose final morphology is perfectly congruent with the natural variability of a comparative sample of E. stenonis specimens. This study shows the potential of using even broken or otherwise fragmentary specimens to guide retrodeformation in badly distorted and damaged specimens. The application of Target Deformation will allow us to increase the availability of comparative specimens in studies of fossil species morphology and evolution, as well as to the study of taphonomic processes. 

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4. Evolutionary origins of the prolonged extant squamate radiation

   https://doi.org/10.1038/s41467-022-34217-5  

   Brownstein, Chase D; Meyer, Dalton L; Fabbri, Matteo; Bhullar, Bhart-Anjan S; Gauthier, Jacques A (December 2022, Nature Communications)

   Abstract Squamata is the most diverse clade of terrestrial vertebrates. Although the origin of pan-squamates lies in the Triassic, the oldest undisputed members of extant clades known from nearly complete, uncrushed material come from the Cretaceous. Here, we describe three-dimensionally preserved partial skulls of two new crown lizards from the Late Jurassic of North America. Both species are placed at the base of the skink, girdled, and night lizard clade Pan-Scincoidea, which consistently occupies a position deep inside the squamate crown in both morphological and molecular phylogenies. The new lizards show that several features uniting pan-scincoids with another major lizard clade, the pan-lacertoids, in trees using morphology were convergently acquired as predicted by molecular analyses. Further, the palate of one new lizard bears a handful of ancestral saurian characteristics lost in nearly all extant squamates, revealing an underappreciated degree of complex morphological evolution in the early squamate crown. We find strong evidence for close relationships between the two new species and Cretaceous taxa from Eurasia. Together, these results suggest that early crown squamates had a wide geographic distribution and experienced complicated morphological evolution even while the Rhynchocephalia, now solely represented by the tuatara, was the dominant clade of lepidosaurs. 

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5. Equus stenonis (Equidae, Mammalia) from the Early Pleistocene of Pantalla (Italy) and the dispersion of stenonine horses in Europe

   https://doi.org/doi:10.4435/BSPI.2020.21  

   Cherin, M. (November 2020, Bollettino della Società paleontologica italiana)

   null (Ed.)

   Describes the Equus record from Pantalla, Italy attributed to the Pleistocene species Equus stenonis. A combination of morphometric analyses of postcrania secure the identification of the species and shows considerable morphometric homogeneity in the species. 

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