The first edentulous ceratosaur from South America

Abstract

The recognition of ontogenetic edentulism in the Jurassic noasaurid Limusaurus inextricabilis shed new light on the dietary diversity within Ceratosauria, a stem lineage of non-avian theropod dinosaurs known for peculiar craniomandibular adaptations. Until now, edentulism in Ceratosauria was exclusive to adult individuals of Limusaurus. Here, an exceptionally complete skeleton of a new toothless ceratosaur, Berthasaura leopoldinae gen. et sp. nov., is described from the Cretaceous aeolian sandstones of the Bauru Basin, Southern Brazil. The specimen resembles adult individuals of Limusaurus by the absence of teeth but based on the unfused condition of several elements (e.g., skull, vertebral column) it clearly represents an ontogenetically immature individual, indicating that it might never have had teeth. The phylogenetic analysis performed here has nested Berthasaura leopoldinae as an early-divergent Noasauridae, not closely related to Limusaurus. It represents the most complete non-avian theropod from the Brazilian Cretaceous and preserves the most complete noasaurid axial series known so far. Moreover, the new taxon exhibits many novel osteological features, uncommon in non-avian theropods, and unprecedented even among South American ceratosaurs. These include not only toothless jaws but also a premaxilla with cutting occlusal edge, and a slightly downturned rostral tip. This indicate that B. leopoldinae unlikely had the same diet as other ceratosaurs, most being regarded as carnivorous. As the ontogenetically more mature specimens of Limusaurus, Berthasaura might have been herbivorous or at least omnivorous, corroborating with an early evolutionary divergence of noasaurids from the ceratosaurian bauplan by disparate feeding modes.

A new Paleogene fossil and a new dataset for waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and avian evolution at the K-Pg Boundary

“…This again contradicts the hypothesis that Anseriformes were ancestrally terrestrial and would explain the presence of reduced rhamphothecal lamellae in extant Anhimidae (Olson and Feduccia, 1980). Anhimidae represent the only known example of rhamphothecal lamellae being present without pedal webbing in extant birds; however, similar lamellae-like ridges have been found in Ornithomimus (Norell et al, 2001; Barrett, 2005), Gallimimus, chelonians, hadrosaurs (Barrett, 2005) and an edentulous ceratosaur (Alves de Souza et al, 2021). A partial correlation between the presence of these ridges and exclusively herbivorous diet among terrestrial chelonians has been found (Bramble, 1974; Pritchard, 1979), suggesting that more prominent ridges were present when more coarse vegetation was eaten.…”

A new Paleogene fossil and a new dataset for waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and avian evolution at the K-Pg Boundary

“…This again contradicts the hypothesis that Anseriformes were ancestrally terrestrial and would explain the presence of reduced rhamphothecal lamellae in extant Anhimidae [ 22 ]. Anhimidae represent the only known example of rhamphothecal lamellae being present without pedal webbing in extant birds; however, similar lamellae-like ridges have been found in Ornithomimus [ 108 , 109 ], Gallimimus, chelonians, hadrosaurs [ 109 ] and an edentulous ceratosaur [ 110 ]. A partial correlation between the presence of these ridges and exclusively herbivorous diet among terrestrial chelonians has been found [ 111 , 112 ], suggesting that more prominent ridges were present when more coarse vegetation was eaten.…”

First definitive record of Abelisauridae (Theropoda: Ceratosauria) from the Cretaceous Bahariya Formation, Bahariya Oasis, Western Desert of Egypt

“…The centrum is craniocaudally shorter than transversely wide, as in many other abelisaurids ( figure 3 ; table 1 ) but contrasting strongly with the much more elongate caudal cervical centra of many non-abelisaurid ceratosaurs such as Berthasaura leopoldinae [ 32 ], Elaphrosaurus bambergi [ 33 – 35 ], Limusaurus inextricabilis [ 36 ], Masiakasaurus knopfleri [ 37 , 38 ] and Vespersaurus paranaensis [ 39 ]. The centrum lacks a ventral keel, as is also the case in Majungasaurus [ 27 ] and Viavenator exxoni [ 28 , 30 ].…”