[D] Tapuiasaurus macedoi [Su] [sG] [T]
Zaher, Pol, Carvalho, Nascimento, Riccomini, Larson, Juarez-Valieri, Pires-Domingues, Silva, da (Jr.) & Campos 2011
Cretaceous Early Aptian
Saurischia Sauropodomorpha Sauropoda Titanosauria
Quiricó Formation (Sanfranciscana Basin), at Embira-Branca Hills near Coracão de Jesus City, in northern Minas Gerais, Brazil.
Advanced titanosaurian sauropods, such as nemegtosaurids and saltasaurids, were diverse and one of the most important groups of herbivores in the terrestrial biotas of the Late Cretaceous. However, little is known about their rise and diversification prior to the Late Cretaceous. Furthermore, the evolution of their highly-modified skull anatomy has been largely hindered by the scarcity of well-preserved cranial remains. A new sauropod dinosaur from the Early Cretaceous of Brazil represents the earliest advanced titanosaurian known to date, demonstrating that the initial diversification of advanced titanosaurians was well under way at least 30 million years before their known radiation in the latest Cretaceous. The new taxon also preserves the most complete skull among titanosaurians, further revealing that their low and elongated diplodocid-like skull morphology appeared much earlier than previously thought.
From ‘‘Tapuia’’, a generic name from the Jês indigenous language family used to designate tribes that inhabited the inner regions of Brazil, and sauros, Greek for lizard. The specific name honors Ubirajara Alves Macedo, who first discovered the deposits near Coracaõ de Jesus.
MZSP-PV (Museu de Zoologia da Universidade de São Paulo) 807, consists of an articulated partial skeleton composed of an almost complete skull and mandible, hyoid apparatus, atlas, axis, five cervical and five dorsal vertebrae and ribs, left sternal plate, right coracoid, right humerus, left radius, ulnae, metacarpals, femora, left fibula, and an almost complete left pes.
Horizon and locality
The skeleton was found in outcrops from the Quiricó Formation (Sanfranciscana Basin), at Embira-Branca Hills near Coracão de Jesus City, in northern Minas Gerais, Brazil.
The age of deposition in the Sanfranciscana Basin is well constrained by two magmatic events to the Lower Cretaceous. It postdates the eruption of the Paraná continental flood basalts dated at 138–128 Ma, and for the most part predates alkalic lavas and volcaniclastic rocks dated at 95–76, which are intercalated with sandstones of the upper part of the basin fill. The lacustrine deposits of the Quiricó Formation, which are in the lower part of the Sanfranciscana sequence, are constrained to the Aptian based on the presence of sarcopterygian fishes, ostracods, and palynomorphs.
An advanced titanosaurian diagnosed by the following autapomorphies: hook-shaped posteroventral process of the quadratojugal; anterior process of the jugal tapering and forming most of the ventral margin of the antorbital fenestra; anterolateral tip of the pterygoid contacts the medial surface of the ectopterygoid. The new taxon is also diagnosed by the following unique combination of characters: deep fossa on the lateral surface of the maxilla between the antorbital fenestra and the subnarial foramen; elongated middle cervical vertebrae; posterior dorsal vertebrae with well-developed prespinal lamina and absence of hyposphene-hypantrum; deep fossae located below intraprezygapohyseal lamina; crescentric-shaped sternal plate; proximodistally long coracoid; elongated ulna and distally expanded radius.