The axial biomechanics of Trigonosaurus pricei (Neosauropoda: Titanosauria) and the importance of the cervical–dorsal region to sauropod high-browser feeding strategy

Trigonosaurus pricei is a small to medium-sized sauropod dinosaur (Sauropoda: Titanosauria) from the Late Cretaceous Bauru Group of Brazil that is known from a significant amount of recovered axial elements [four cervical vertebrae, 10 dorsal vertebrae, sacrum (MCT 1488-R), and 10 caudal vertebrae (MCT 1719-R)]. In this biomechanical work, we approach the hypothesis of the cartilaginous neutral pose and the range of motion of the axial series of Trigonosaurus. The results show that this sauropod could be capable of high elevation of the neck resulting from morphological adaptations of the cervicodorsal region on dorsal (D) vertebrae D2 and D3 (e.g. postzygapophyses of D2 positioned over the vertebral centrum and prezygapophyses of D3 over the anterior vertebral centrum). This implies that D2 articulates (cartilaginous neutral posture) with D3 only at a strong dorsally directed angle, resulting in a shift in the direction of the neck to a more elevated posture. Furthermore, the tail attributed to Trigonosaurus as a paratype could be oriented in the horizontal ‘direction’ and presented a sigmoidal ‘shape’. This work contributes generally to the understanding of variation in the body plan of sauropods and, more specifically, to the feeding strategy of small and medium-sized titanosaurs from semi-arid regions of Gondwana

Palaeohistology and palaeopathology of an Aeolosaurini (Sauropoda: Titanosauria) from Morro do Cambambe (Upper Cretaceous, Brazil)

Altres ajuts: CAISEP (Comisión de Ayudas a la Investigación de la Sociedad Española de Paleontología) project #2018-07153A recent publication of fossil bones of titanosaurs assigned to Aeolosaurini from the Morro do Cambambe site (Mato Grosso state, Brazil, Upper Cretaceous) reported anomalous growth in some of them. Here, we present osteohistological sections of elements to understand not only the microstructure and growth of such bones, but also the nature of those anomalies. The primary bone of all specimens consisted of a variation of the fibrolamellar complex, with the inner cortex being rich in woven bone with dispersed longitudinal canals, while the outer cortex was parallel-fibred with rows of longitudinal canals, interlayered by Lines of Arrested Growth (LAGs). We identified a maximum of two LAGs in the cervical rib and haemal arch, and four in the dorsal rib. The haemal arch shows an External Fundamental System (EFS) in most sections. The advanced remodelling and variation of the fibrolamellar bone in the cortex suggests that all the specimens represent individuals that reached sexual maturity. However, the haemal arch was distinct due to the wide distribution of EFS. The dorsal rib exhibited periosteal and endosteal outgrowth. Such microstructure was assigned to a reactive bone due to an intra-thoracic infection (a pneumonia, probably related to a tuberculosis), which is the first report in a non-avian dinosaur. The microstructure resembles the medullary bone recovered in dinosaurs, which suggests that further studies of medullary bone in thoracic bones should also regard the pathological cases.En una reciente publicación de los huesos fósiles de titanosaurios asignados al clado Aeolosaurini provenientes del yacimiento de Morro do Cambambe (estado de Mato Grosso, Brasil, Cretácico Superior), se reconocieron anormalidades en el crecimiento de algunos de ellos. En el presente trabajo presentamos cortes osteohistológicos de elementos para entender no sólo la microestructura y crecimiento de los mismos, sino también la naturaleza de aquellas anomalías. Entre ellos, seleccionamos una costilla cervical y una costilla dorsal media posterior, así como un arco hemal. El hueso primario de todos los especímenes comprendía una variación del complejo fibrolamelar, siendo la corteza interna rica en tejido reticular óseo con canales longitudinales dispersos, mientras que la corteza externa tenía fibras paralelas con hileras de canales longitudinales, intercaladas por líneas de crecimiento detenido. Identificamos un máximo de dos líneas de crecimiento detenido tanto en la costilla cervical como en el arco hemal, y cuatro en la costilla dorsal. El arco hemal muestra un Sistema Externo Fundamental en la mayoría de las secciones. La remodelación avanzada y la variación del hueso fibrolamelar en la corteza, se sugiere que todas los especímenes alcanzaron la madurez sexual. Sin embargo, el arco hemal fue distinto debido a la amplia distribución de Sistema Externo Fundamental. Con base en la microestructura, identificamos un semaforonte subadulto, y probablemente a un adulto. La costilla dorsal mostró una excrecencia perióstica y endosteal. Dicha microestructura se ha identificado con un hueso reactivo a una infección intratorácica (una neumonía, probablemente relacionada con una tuberculosis), que es el primer informe de un dinosaurio no aviano. La microestructura se asemeja al hueso medular recuperado en los dinosaurios, lo que sugiere que los estudios posteriores del hueso medular en los huesos torácicos también deberían considerar los casos patológicos

A New Giant Titanosauria (Dinosauria: Sauropoda) from the Late Cretaceous Bauru Group, Brazil

<div><p>Titanosaurian dinosaurs include some of the largest land-living animals that ever existed, and most were discovered in Cretaceous deposits of Argentina. Here we describe the first Brazilian gigantic titanosaur, <i>Austroposeidon magnificus</i> gen. et sp. nov., from the Late Cretaceous Presidente Prudente Formation (Bauru Group, Paraná Basin), São Paulo State, southeast Brazil. The size of this animal is estimated around 25 meters. It consists of a partial vertebral column composed by the last two cervical and the first dorsal vertebrae, all fairly complete and incomplete portions of at least one sacral and seven dorsal elements. The new species displays four autapomorphies: robust and tall centropostzygapophyseal laminae (cpol) in the last cervical vertebrae; last cervical vertebra bearing the posterior centrodiapophyseal lamina (pcdl) bifurcated; first dorsal vertebra with the anterior and posterior centrodiapophyseal laminae (acdl/pcdl) curved ventrolaterally, and the diapophysis reaching the dorsal margin of the centrum; posterior dorsal vertebra bearing forked spinoprezygapophyseal laminae (sprl). The phylogenetic analysis presented here reveals that <i>Austroposeidon magnificus</i> is the sister group of the Lognkosauria. CT scans reveal some new osteological internal features in the cervical vertebrae such as the intercalation of dense growth rings with camellae, reported for the first time in sauropods. The new taxon further shows that giant titanosaurs were also present in Brazil during the Late Cretaceous and provides new information about the evolution and internal osteological structures in the vertebrae of the Titanosauria clade.</p></div

Measurements of the major elements of <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>Dashed lines indicate portions which could not be measured since they are not preserved.</p

Cervical rib of <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>(A) Internal and (B) external views. Scale bar: 100mm.</p

The tentatively 3D reconstruction of the internal pneumatic structures in <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>(A) The last cervical vertebra (Cv13) in posterolateral view. (B) First dorsal vertebra in left posterolateral view. The internal pneumatic connections suggest a possible interconnection of all the internal pneumatic structures throughout the entire vertebral body (light green). Scale bar: 100mm.</p

Detail of the cervical rib of <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>Red arrows show the scars for connective tissue. Scale bar: 50mm.</p

First dorsal vertebra (D1) of <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>(A) In anterior, (B) left anterolateral, (C) dorsal, (D) and posterior views. Abbreviations: cprl, centroprezygapophyseal lamina; ns, neural spine; prsl, prespinal lamina; prz, prezygapophysis; poz, postzygapophysis; spol, spinepostzygapophyseal lamina. Scale bar: 100mm.</p

Additonal elements of dorsal and sacral vertebrae of <i>Austroposeidon magnificus</i> gen. et sp. nov.

<p>(A) Left transverse process of a posterior dorsal vertebra, in anterior, (B) posterior views. (C) Left prezygapophysis from the posterior dorsal vertebra, with dark lines showing the bifurcated spinoprezygapophiseal lamina. (D) Sacral element, with white arrows indicating the suture between the sacral transverse process and the sacral rib, and the black arrow the sacral rib. Abbreviations: prdl, prezygodiapophyseal lamina; prz, prezygapophysis; podl, postzygodiapophyseal lamina; prdl, prezygodiapophyseal lamina; spdl, spinodiapophyseal lamina; sprl, spinoprezygapophyseal lamina. Scale bar: 100mm.</p

Cervical vertebra (Cv 12) of <i>Austroposeidon magnificus</i> gen. et nov. sp.

<p>(A) Left lateral and (B) anterior views. Abbreviations: acdl, anterior centrodiapophyseal lamina; acpl, anterior centroparapophyseal lamina; cprl, centroprezygapophyseal lamina; d, diapophysis; prz, prezygapophysis; prdl, prezygodiapophyseal lamina; prsl, prespinal lamina; s, neural spine; sprl, spinoprezygapophyseal lamina. Scale bar: 100mm.</p