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. 2017 Aug 16;284(1860):20171219.
doi: 10.1098/rspb.2017.1219.

A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs

José L Carballido  1 , Diego Pol  2 , Alejandro Otero  3 , Ignacio A Cerda  4 , Leonardo Salgado  4 , Alberto C Garrido  5   6 , Jahandar Ramezani  7 , Néstor R Cúneo  2 , Javier M Krause  2
Affiliations

A new giant titanosaur sheds light on body mass evolution among sauropod dinosaurs

José L Carballido et al. Proc Biol Sci. .

Abstract

Titanosauria was the most diverse and successful lineage of sauropod dinosaurs. This clade had its major radiation during the middle Early Cretaceous and survived up to the end of that period. Among sauropods, this lineage has the most disparate values of body mass, including the smallest and largest sauropods known. Although recent findings have improved our knowledge on giant titanosaur anatomy, there are still many unknown aspects about their evolution, especially for the most gigantic forms and the evolution of body mass in this clade. Here we describe a new giant titanosaur, which represents the largest species described so far and one of the most complete titanosaurs. Its inclusion in an extended phylogenetic analysis and the optimization of body mass reveals the presence of an endemic clade of giant titanosaurs inhabited Patagonia between the Albian and the Santonian. This clade includes most of the giant species of titanosaurs and represents the major increase in body mass in the history of Titanosauria.

Keywords: Cretaceous; Gondwana; Patagonia; Titanosauria; taphonomy.

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Conflict of interest statement

We declare we have no competing interests.

Figures

Figure 1.
Figure 1.
Reconstructed skeleton and body silhouette of Patagotitan mayorum showing preserved elements from the holotype and paratypic specimens.
Figure 2.
Figure 2.
Representative elements of Patagotitan mayorum. (a) Middle cervical vertebra (MPEF-PV 3400/2; 5th?) in right lateral view. (b,c) Anterior dorsal vertebra (MPEF-PV 3400/5; 2nd) in anterior (b) and left lateral (c) views. (d,e) Anterior dorsal vertebra (MPEF-PV 3400/6; 3rd) in anterior (d) and posterior (e) views. (f,g) Posterior dorsal vertebra (MPEF-PV 3400/10; 10th?) in posterior (f) and right lateral (g) views. (h–j) First caudal vertebra in anterior (h), left lateral (i) and posterior (j) views. (k–m) Anterior caudal vertebra (MPEF-PV 3400/16; 8th?) in anterior (k), left lateral (l) and posterior (m) views. (n) Middle caudal vertebra in left lateral view. (o) Posterior caudal vertebra in left lateral view). (p) Right scapula (MPEF-PV 3400/23) and coracoid (MPEF-PV 3400/24) in lateral view. (q,r) Left humerus (MPEF-PV 3397) in anterior (q) and posterior (r) views. (s–u) Right femur (MPEF-PV 4400/26) in posterior (s), proximal (t) and distal (u) view. Vertebrae elements were oriented with their neural canal horizontally placed. 4t, fourth trochanter; ap, acromion process; cf, coracoid foramen; CPOL, centrpopostzygapophyseal lamina; CPRL, centroprezygapophyseal lamina; dp, diapophysis; dpc, deltopectoral crest; ec, epicondyle; fc, fibular condyle; fh, femur head; gl, glenoid; hh, humeral head; igl, infraglenoid lip; ms muscle scar; PCDL, posterior centrodiapophyseal lamina; pdt, posteriorly directed tips; pl, pleurocoel; plb, posterolateral bulge; pls, primary lateral surface; PODL, postzygodiapophyseal lamina; POSL, postspinal lamina; poz, postzygapophysis; pp, parapohysis; PPDL, paradiapophyseal lamina; PRDL, prezygodiapophyseal lamina; PRSL, prezigapophyseal lamina; prz, prezygapophysis; rc, radial condyle; scb, scapular blade; sls, secondary lateral surface; SPOL, spinopostzygapophyseal lamina; SPRL, spinoprezygapophyseal lamina; tc, tibial condyle; tp, transverse process; tpal, thin paired anterior laminae; uc, ulnar condyle; vmp, ventromedial process.
Figure 3.
Figure 3.
Phylogenetic relationships of Patagotitan mayorum and body mass evolution in Somphospondyli. Reduced strict consensus tree (excluding Sauroposeidon, Ligabuesaurus and Trigonosaurus) calibrated against age. Branch colours indicates body mass inferred through scaling equation [37] and continuous character optimization in TNT (ancestral branches). See electronic supplementary material for complete phylogenetic analysis, body mass optimization and taxon definitions followed here.
See this image and copyright information in PMC

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