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We here describe Terastiodontosaurus marcelosanchezi , a new amphisbaenian genus and species from the Eocene of Chambi, Tunisia. Using micro-computed tomography (μCT), we document the peculiar anatomy of the new taxon, which is characterized by extreme dental morphology, including one massive tooth on the maxilla and dentary, flat cheek teeth, and an array of other diagnostic features that readily differentiate it from all other amphisbaenians. We also redescribe the oldest named African amphisbaenian, Todrasaurus gheerbranti , from the late Palaeocene of Morocco, using μCT. Phylogenetic analysis recovers Terastiodontosaurus and Todrasaurus as sister taxa and provides strong support for a sister-group relationship of those two large-toothed amphisbaenians with extant Trogonophis. Accordingly, Todrasaurus shows that the divergence of crown Trogonophidae occurred much earlier than currently thought. Our survey of μCT scans reveals that Terastiodontosaurus , Todrasaurus , and Trogonophis are characterized by a great enamel thickness on their teeth, a feature that is absent in other examined amphisbaenians. Size estimates show that Terastiodontosaurus was the largest known amphisbaenian ever to have lived, with an estimated skull length of >5 cm. Based on new muscle data of Trogonophis , we estimate very high bite forces for Terastiodontosaurus , which would allow it to crush a wide variety of snails. [ABSTRACT FROM AUTHOR]

We describe two exceptionally preserved fossil snakes from the Eocene Konservat-Lagerstätte of Geiseltal, located in the state of Saxony-Anhalt, Germany. The two snake specimens, GMH LIX-3-1992 and GMH XXXVIII-20-1964, can be confidently identified as booids based on general morphology and were thus compared to other geographically and/or temporally close fossil booids. We found that GMH LIX-3-1992 is morphologically very similar to Eoconstrictor spinifer , also from Geiseltal, and to Eoconstrictor fischeri , from the middle Eocene of Messel, but differs from both in a number of cranial and vertebral features. Based on these differences we erect the new species Eoconstrictor barnesi sp. nov. ; GMH XXXVIII-20-1964 is very similar to GMH LIX-3-1992 and the two differ only in features that are likely ontogenetic. Phylogenetic analyses of snakes using maximum parsimony and Bayesian inference on datasets inclusive of both morphological and molecular data consistently support a close affinity of E. barnesi to E. fischeri and E. spinifer. Our preferred phylogenetic hypothesis places the three species of Eoconstrictor in a clade that is sister to Neotropical Boidae, a result consistent with previous studies. The genus Eoconstrictor could provide an important calibration point for molecular clock studies of booids and snakes in general. [ABSTRACT FROM AUTHOR]

We here report an anterior trunk vertebra of a large snake that we tentatively refer to Palaeophis africanus. The vertebra comes from lower middle Eocene deposits of the El Breij Depression, in the Sahara Desert of southern Morocco. It is principally characterised by weak lateral compression; horizontality of the cotyle-condyle axis; dorsoventrally thick zygosphene; lower pterapophyses with an upper edge that remains lower than that of the zygosphene in lateral view; a rather reduced neural canal; very distinct and prominent interzygapophyseal crests; low position of the diapophyses; and the presence of two hypapophyses. This occurrence adds to the geographic distribution of Palaeophis africanus, which has been formerly identified from Nigeria, Togo, Angola, and South America, and represents an additional Palaeophis species for the Moroccan fossil record. [ABSTRACT FROM AUTHOR]

We report avian cervical vertebrae from the Quercy fissure fillings in France, which are densely covered with villi‐like tubercles. Two of these vertebrae stem from a late Eocene site, another lacks exact stratigraphic data. Similar cervical vertebrae occur in avian species from Eocene fossils sites in Germany and the United Kingdom, but the new fossils are the only three‐dimensionally preserved vertebrae with pronounced surface sculpturing. So far, the evolutionary significance of this highly bizarre morphology, which is unknown from extant birds, remained elusive, and even a pathological origin was considered. We note the occurrence of similar structures on the skull of the extant African rodent Lophiomys and detail that the tubercles represent true osteological features and characterize a distinctive clade of Eocene birds (Perplexicervicidae). Micro‐computed tomography (μCT) shows the tubercles to be associated with osteosclerosis of the cervical vertebrae, which have a very thick cortex and much fewer trabecles and pneumatic spaces than the cervicals of most extant birds aside from some specialized divers. This unusual morphology is likely to have served for strengthening the vertebral spine in the neck region, and we hypothesize that it represents an anti‐predator adaptation against the craniocervical killing bite ("neck bite") that evolved in some groups of mammalian predators. Tuberculate vertebrae are only known from the Eocene of Central Europe, which featured a low predation pressure on birds during that geological epoch, as is evidenced by high numbers of flightless avian species. Strengthening of the cranialmost neck vertebrae would have mitigated attacks by smaller predators with weak bite forces, and we interpret these vertebral specializations as the first evidence of "internal bony armor" in birds. [ABSTRACT FROM AUTHOR]