A diverse Late Cretaceous vertebrate tracksite from the Winton Formation of Queensland, Australia

The Upper Cretaceous ‘upper’ Winton Formation of Queensland, Australia is world famous for hosting Dinosaur Stampede National Monument at Lark Quarry Conservation Park, a somewhat controversial tracksite that preserves thousands of tridactyl dinosaur tracks attributed to ornithopods and theropods. Herein, we describe the Snake Creek Tracksite, a new vertebrate ichnoassemblage from the ‘upper’ Winton Formation, originally situated on Karoola Station but now relocated to the Australian Age of Dinosaurs Museum of Natural History. This site preserves the first sauropod tracks reported from eastern Australia, a small number of theropod and ornithopod tracks, the first fossilised crocodyliform and ?turtle tracks reported from Australia, and possible lungfish and actinopterygian feeding traces. The sauropod trackways are wide-gauge, with manus tracks bearing an ungual impression on digit I, and anteriorly tapered pes tracks with straight or concave forward posterior margins. These tracks support the hypothesis that at least one sauropod taxon from the ‘upper’ Winton Formation retained a pollex claw (previously hypothesised for Diamantinasaurus matildae based on body fossils). Many of the crocodyliform trackways indicate underwater walking. The Snake Creek Tracksite reconciles the sauropod-, crocodyliform-, turtle-, and lungfish-dominated body fossil record of the ‘upper’ Winton Formation with its heretofore ornithopod- and theropod-dominated ichnofossil record

Photographic Atlas and Three-Dimensional Reconstruction of the Holotype Skull of Euhelopus zdanskyi with Description of Additional Cranial Elements

Background: Euhelopus zdanskyi is one of relatively few sauropod taxa known from an almost complete skull and mandible. Recent phylogenetic analyses suggest that Euhelopus is a somphospondylan titanosauriform, and that it is a member of the clade (Euhelopodidae) which is the sister taxon to the hugely successful, dominantly Cretaceous sauropod group Titanosauria. Methodology/Principal Findings: The skull elements of Euhelopus were CT scanned at Uppsala Akademiska Sjukhuset. Three-dimensional models of the elements were constructed from the DICOM data using Mimics 14.0, InVesalius 3.0, and GeoMagic Studio 2012, the skull was rearticulated in Rhinoceros 4.0, and the final version was rendered in GeoMagic Studio 2012. Conclusions/Significance: The fact that relatively complete sauropod skulls are so rare in the fossil record, particularly among titanosauriforms, means that the skulls that are known should be as thoroughly described and well-illustrated as possible. This contribution supplements previous descriptions of the cranial elements of Euhelopus, one of the few euhelopodid taxa for which cranial material is known, by presenting a comprehensive photographic atlas of the skull elements to facilitate a better understanding of their morphology. We describe several elements which have been overlooked in past studies of Euhelopus, and also provide as accurate a reconstruction of the skull as possible (in the absence of the braincase), the most significant components of which are the articulations of the palate and the mandible

Comparative Three-Dimensional Moment Arm Analysis of the Sauropod Forelimb: Implications for the Transition to a Wide-Gauge Stance in Titanosaurs

The evolution of extraordinarily large size among Sauropoda was associated with a number of biomechanical adaptations. Changes in muscle moment arms undoubtedly accompanied these adaptations, but since muscles rarely fossilize, our ability to understand them has been restricted. Here, we use three-dimensional (3D) musculoskeletal modeling to reconstruct and quantitatively assess leverage of forelimb muscles in the transition from the narrow-gauge stance of basal sauropods to a wide-gauge stance in titanosaurs. A comparative analysis is conducted on three neosauropods: the narrow-gauge diplodocid Apatosaurus louisae, the intermediate-gauge titanosariform Giraffatitan brancai, and the wide-gauge titanosaur Diamantinasaurus matildae. In this study, moment arm magnitudes and corresponding morphological evidence indicates multiple changes across the narrow-gauge to wide-gauge transition in sauropods. High shoulder adduction was found in Diamantinasaurus, suggesting functional changes for supporting a wider stance and a limb less aligned with ground reaction force. High leverage in shoulder extension of Diamantinasaurus and Giraffatitan is possibly related to the increased use of the forelimb in forward propulsion with an anterior shift in center of mass. In addition, the prominence of the olecranon process in Diamantinasaurus produced high moment arm leverage in elbow flexion and extension, suggesting titanosaurs might have maintained a more flexed forelimb posture and displayed an increased degree of maneuverability. Other results are more variable between taxa but still indicate smaller scale changes. A sensitivity analysis was also conducted to measure the reliability of our models and test specific uncertainties within the modeling process, as well as other uncertainties uncovered during analysis

Right premaxilla and maxilla (PMU 24705/1b [formerly PMU R 233 a]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E) and medial (F) views.

<p>Right premaxilla and maxilla (PMU 24705/1b [formerly PMU R 233 a]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E) and medial (F) views.</p

Reconstructed left pterygoid (PMU 24705/1l [formerly PMU R 233 ä] and PMU 24705/1w [formerly PMU R 233 ö]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), left lateral (C), ventral, (D), caudal (E), and medial (F) views.

<p>Note that the point of contact between the two portions is offset – the two elements no longer attach perfectly due to post mortem deformation of the element.</p

Right lacrimal (PMU 24705/1f [formerly PMU R 233 β]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E), and medial (F) views.

<p>Right lacrimal (PMU 24705/1f [formerly PMU R 233 β]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E), and medial (F) views.</p

PMU 24705/1t (formerly PMU R 233 p), a probable splenial.

<p>PMU 24705/1t (formerly PMU R 233 p), a probable splenial.</p

Right postorbital (PMU 24705/1 g [formerly PMU R 233 a]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E), and medial (F) views; and PMU 24705/1v (formerly PMU R 233 y), a portion of bone still partially embedded in matrix which may be the tapered end of the jugal process of the postorbital (G).

<p>Right postorbital (PMU 24705/1 g [formerly PMU R 233 a]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal (B), right lateral (C), ventral (D), caudal (E), and medial (F) views; and PMU 24705/1v (formerly PMU R 233 y), a portion of bone still partially embedded in matrix which may be the tapered end of the jugal process of the postorbital (G).</p

Left palatine (PMU 24705/1 m [formerly PMU R 233 δ]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal, (B), left lateral (C), ventral (D), caudal (E), and medial (F) views.

<p>Left palatine (PMU 24705/1 m [formerly PMU R 233 δ]) of <i>Euhelopus zdanskyi</i> in rostral (A), dorsal, (B), left lateral (C), ventral (D), caudal (E), and medial (F) views.</p

Reconstruction of the skull of <i>Euhelopus zdanskyi</i> based on the holotype elements (PMU 24705/1 [formerly PMU R 233]) from “exemplar a” in rostral (A), dorsal (B), left lateral (C), ventral (D), caudal (E), and medial (F) views; the right side of the skull has been removed in medial view to show the organisation of the palatal and mandibular elements.

<p>More complete and/or better preserved elements were used in this reconstruction when both left and right elements were preserved. The reconstructions of the skull provided by Wiman <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079932#pone.0079932-Wiman1" target="_blank">[43]</a> (G) and Mateer and McIntosh <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0079932#pone.0079932-Mateer1" target="_blank">[44]</a> (H) are presented, as is a line drawing of the skull as reconstructed in this work (I).</p