View Images A life restoration of the newfound titanosaur Savannasaurus elliottorum, based on the defining specimen and comparisons with other titanosaurs 
 
 Image By Travis Tischler, Australian Age of Dinosaurs Museum Natural History 
 
 To get to Australia, giant dinosaurs known as titanosaurs may have had to trek across an even more down-under continent: Antarctica. 
 
 That’s the conclusion drawn by a new family tree for sauropods, a group of herbivorous long-necked dinosaurs that includes the largest land animals to ever walk the Earth. The report is based on new sauropod fossils found in Australia that are between 95 and 98 million years old, including a new genus and species dubbed Savannasaurus elliottorum. 
 
 The findings—published October 20 in Scientific Reports—suggest that Australia’s sauropods, including titanosaurs, didn’t get to the continent until about a hundred million years ago, tens of millions of years after other types of dinosaurs arrived. 
 
 Moreover, the family tree strongly suggests that Australia’s sauropods descended from South American forebears. If those results hold, then it means that sauropods must have traveled by land from South America to Australia during the Cretaceous, when the drifting continents were almost in the positions we see today. 
 
 The only available land route at the time? An ice-free Antarctica, made hospitable to sauropods by an ancient bout of natural global warming. 
 
 “By plotting the evolution of these sauropods against changes in the positions of the continents, we’ve possibly been able to constrain when these titanosaurs migrated,” says study author Stephen Poropat, a paleontologist with the Australian Age of Dinosaurs Museum in Winton, Queensland, Australia. 
 
 Charting titanosaurs’ Antarctic trek wouldn’t have been possible without the newly described bones, a crucial addition to Australia’s fossil record, which has long been thin on sauropods. In addition to Savannasaurus, the semicomplete remains include the first sauropod skull ever found in Australia, which belongs to a previously known species called Diamantinasaurus matildae. 
 
 “Australia has always been one of those unfortunate black holes,” wrote Stephen Brusatte, a University of Edinburgh paleontologist who wasn’t involved with the study, in an emailed statement. “We just know so little about the dinosaurs that lived here, and that has made it difficult to study how dinosaurs moved around the globe.” 
 
 He adds that “the new skeleton of Savannasaurus … gives us a really nice glimpse at what the giant, long-necked sauropods that used to call Australia home would have looked like.” 
 
 A Dinosaur That Stood Apart 
 
 As Savannasaurus’s name suggests, its bones were found in a grassland in eastern Australia in 2005. The remains were first spotted by David Elliott, an Australian sheep farmer and dinosaur enthusiast who has revitalized the study of Australian fossils, founding the Australian Age of Dinosaurs Museum. 
 
 Excavations in 2005 turned up more of Savannasaurus, encased in rock harder than concrete. It took years of work from volunteers to liberate the bones from their casing, and more years still for Poropat and his colleagues to analyze the remains. 
 
 “It’s been a long time coming to get this dinosaur described, but it’s extremely exciting,” Elliott says in a statement. “It’s quite unlike most of the other [sauropods] around the world.” 
 
 Like all sauropods, Savannasaurus had hollow bones and air sacs throughout its body, an evolutionary attempt to lighten its enormous skeleton. The dinosaur probably stood about 20 feet tall and may have weighed between 15 to 20 tons. 
 
 But in some respects, Savannasaurus stands apart—literally. Study co-author Paul Upchurch, a University College London paleobiologist and sauropod expert, says that the dinosaur’s hips were extremely wide, possibly giving it more stability and flexibility when tromping around in inland environments. 
 
 Its pelvis also strikes Upchurch as peculiar. “There are places where the bones are paper-thin,” he says. “I’ve never seen such a thin sheet of bone in a sauropod pelvis.” 
 
 Poropat adds that the dinosaur’s belly would have been enormous, suggesting that its digestive system would have been convoluted and extensive—absorbing more nutrients from its food than its svelter relatives. 
 
 “Savannasaurus seems like a giant fermenting vat … [and] like a long-necked, long-legged hippo, in terms of the actual build of the body,” Poropat says. 
 
 But both researchers say that much more work remains to understand Savannasaurus and its relatives—and how they all got to the continent. 
 
 Poropat says that the team will soon double back and comprehensively describe the new fossils, confirming the species assignments. And Upchurch says the team is already improving its just published family tree, which should help scientists better grasp how the titanic animals lived, died, and spread across ancient Earth. ||||| 95m-year-old Savannasaurus elliottorum leads researchers to propose new theory of how sauropods spread around the world 
 
 A new species of giant herbivorous dinosaur has been found in outback Australia, helping to rewrite the textbooks on how the gentle giants spread around the globe. 
 
 The species is a member of the group of dinosaurs known as sauropods – such as the brontosaurus, which have long necks and four thick, pillar-like legs. It belongs to a subgroup called “titanosaurs”, thought to have evolved in South America. 
 
 Monster haul: Three new dinosaurs discovered Read more 
 
 Named Savannasaurus elliottorum after the savannah landscape it was found in, and David Elliott, who discovered the bones on his sheep station in central Queensland, its 40-or-so fossilised bones make up one of the most complete sauropod skeletons found to date in Australia. 
 
 The species was reported on Thursday in the journal Scientific Reports alongside a specimen of another similar but previously described species, known as Diamantinasaurus matildae. 
 
 Together, the two specimens led researchers to redescribe the evolutionary tree of sauropods, and propose a new theory of how they spread across the ancient megacontinent of Gondwana, which joined Australia, Africa, Antarctica and South America. 
 
 The 95m-year-old savannasaurus specimen, nicknamed Wade, was found by Elliott, who runs the Australian Age of Dinosaurs museum on his farm near Winton. It documents a series of other dinosaur discoveries dating back nearly 20 years. 
 
 
 
 “I was mustering sheep for crutching,” Elliott said. “It was in 2006 and I found a little toe bone. I thought it was a theropod dinosaur, actually – it looked like a bit of a limb bone. I was really excited about it. It turned out to be a sauropod.” 
 
 Elliot’s wife, Judy, looked at two parts of the bone and saw they fitted together, revealing it was a single complete toe of a sauropod, rather than two different parts of a theropod toe. 
 
 Over the following years, the Elliott family, scientists and volunteers excavated 17 pallets’ worth of fossil fragments, reconstructing about 20% of a complete skeleton. The dinosaur was found to be between 12 and 15 metres long. 
 
 Cretaceous dinosaur footprints uncovered on Western Australian beach Read more 
 
 About the same time, Elliott discovered part of another sauropod skeleton, which turned out to be a specimen of a species called Diamantinasaurus matildae. The find included the only skull of that species ever seen. 
 
 The two discoveries helped the researchers redraw the evolutionary tree of related dinosaurs, helping them to reconstruct their movement around the world. 
 
 
 
 “The more anatomical information you can derive from a specimen, the more accurately you can place it on the dinosaur family tree,” said Stephen Poropat, a paleontologist who works with the Australian Age of Dinosaurs museum. 
 
 
 
 With the new information, Poropat and colleagues found the diamantinasaurus was a less advanced member of the family than previously thought. The new savannasaurus was also to found to be a primitive member of the group. 
 
 
 
 The evolutionary analysis, which compared the specimens with similar ones in South America, meant there was a small window between 100m and 105m years ago when an ancestor of the two dinosaurs must have crossed over land from South America, through Antarctica, to Australia. 
 
 While the evolutionary analysis suggested the dinosaurs only made the journey about 100m years ago, the position of the continents at the time showed it should have been possible earlier. 
 
 “We realised there must have been some sort of barrier to them dispersing between South America and Australia before about 105m years ago,” Poropat said. 
 
 Oldest fossil of bird's voicebox gives new hint at soundscape of the Cretaceous Read more 
 
 The researchers argued the cool climate of the polar region could have been that barrier. And a period of global warming that occurred about 105m years ago could have made the polar region more suitable to the dinosaurs. “Whether by accident or by choice, some of them found themselves in Australia,” said Poropat. 
 
 John Long, a paleontologist from Flinders University in Australia who wasn’t involved in the research, said the find was amazing. 
 
 “The Winton formation keeps yielding this amazing material and it’s showing such a great diversity of titanosaurs that were around in Australia in this middle cretaceous period,” Long said. 
 
 He said it was previously thought that most Australian dinosaurs travelled south from Asia. “It’s now emerging that most of our dinosaurs have a South American affinity,” he said. 
 
 The researchers’ theory about climate change allowing the dinosaurs to spread was interesting and “fair enough”. “It’s only putting an idea out there that needs more evidence.” 
 
 Long said if the theory were correct, it could be confirmed by other finds. 
 
 “Based on that, we could make the prediction that we would find more exciting dinosaurs that occur in South America. Like, for example, the horned carnotaurus – it’s a theropod meat-eating dinosaur with horns on its head.” ||||| Systematic Palaeontology 
 
 Dinosauria Owen, 1842 
 
 Saurischia Seeley, 1887 
 
 Sauropoda Marsh, 1878 
 
 Macronaria Wilson and Sereno, 1998 
 
 Titanosauriformes Salgado, Coria and Calvo, 1997 
 
 Titanosauria Bonaparte and Coria, 1993 
 
 Savannasaurus elliottorum gen. et sp. nov. 
 
 Etymology 
 
 From the Spanish (Taino) zavana (savanna), in reference to the countryside in which the specimen was found, and the Greek σαῦρος (lizard). The species name honours the Elliott family for their ongoing contributions to Australian palaeontology. 
 
 Holotype 
 
 Australian Age of Dinosaurs Fossil (AODF) 660: one posterior cervical vertebra; several cervical ribs; eight dorsal vertebrae; several dorsal ribs; at least four coalesced sacral vertebrae with processes; at least five partial caudal vertebrae; fragmentary scapula; left coracoid; left and right sternal plates; incomplete left and right humeri; shattered ulna; left radius; right metacarpals I–V; left metacarpal IV; two manual phalanges; fragments of left and right ilia; left and right pubes and ischia, fused together; left astragalus; right metatarsal III; and associated fragments. This disarticulated skeleton was found within a single concretion. The dorsal vertebrae and ribs were in approximate order but were somewhat scattered immediately in front of the incomplete sacrum and puboischiadic sheet (Fig. 3). 
 
 Figure 3: Savannasaurus elliottorum gen. et sp. nov., holotype specimen AODF 660. Type site map showing the approximate association of the bones. Scale bar = 1 m. Full size image 
 
 Type horizon and locality 
 
 Winton Formation (Cenomanian–lower Turonian26); Australian Age of Dinosaurs Locality (AODL) 82 (the “Ho-Hum site”), Belmont Station, Winton, Queensland, Australia. 
 
 Diagnosis 
 
 Wide-bodied titanosaur diagnosed by the following autapomorphies: (1) anterior-most caudal centra with shallow lateral pneumatic fossae; (2) sternal plate with straight lateral margin (reversal); (3) metacarpal IV distal end hourglass shaped; (4) pubis with ridge extending anteroventrally from ventral margin of obturator foramen on lateral surface; and (5) astragalus proximodistally taller than mediolaterally wide or anteroposteriorly long. 
 
 Description 
 
 The sole preserved cervical vertebra of Savannasaurus is opisthocoelous and possesses a deep lateral pneumatic foramen. It bears a mid-line ventral keel, a feature uncommon among Macronaria27. The cervical ribs are elongate, such that they overlap at least two vertebrae additional to the one to which they were attached. All preserved dorsal centra are opisthocoelous and show camellate internal texture as in Titanosauriformes28,29. They possess deep, posteriorly acuminate, lateral pneumatic foramina that are set within fossae (Fig. 4a–e); the latter characteristic is mainly restricted to somphospondylans29. All preserved dorsal vertebrae possess ventrolateral ridges but lack ventral keels; both keels and ridges are present in Opisthocoelicaudia30 and Diamantinasaurus22. As in most advanced titanosaurs27,31, hyposphenes and hypantra are absent in all preserved vertebrae of Savannasaurus. The dorsal neural spines are not bifid, distinguishing Savannasaurus from Opisthocoelicaudia30. The dorsal neural spines are angled posterodorsally at 45° to the long axis of the centrum in the anterior-most vertebrae, a synapomorphy of Somphospondyli29; this angle decreases along the column, with the posterior-most spines sub-vertical. As in all members of Titanosauriformes29, the dorsal ribs bear proximal pneumatic cavities. The incomplete sacrum, comprising at least four vertebrae with lower sacral acetabular processes, is over one metre wide transversely at its narrowest point (Fig. 4f), contributing to the wide-hipped appearance of Savannasaurus. All preserved caudal vertebrae are amphicoelous (Fig. 4g,h), distinguishing Savannasaurus from most titanosaurs32. The anterior-most caudal vertebra preserved bears shallow lateral pneumatic fossae, unlike those of most somphospondylans27, including Wintonotitan33. Within Macronaria, the presence of such fossae has been regarded as a synapomorphy of Brachiosauridae (or a slightly less inclusive clade)31; as such, the discovery of fossae in the anterior caudal vertebrae of Savannasaurus indicates that this feature was more widespread within Titanosauriformes. 
 
 Figure 4: Savannasaurus elliottorum gen. et sp. nov., holotype specimen AODF 660. (a–e) Dorsal vertebrae (left lateral view). (f) Sacrum (ventral view). (g,h) Caudal vertebrae (left lateral view). (i) Left coracoid (lateral view). (j) Right sternal plate (ventral view). (k) Left radius (posterior view). (l) Right metacarpal III (anterior view). (m) Left astragalus (anterior view). (n) Coossified right and left pubes (anterior view). A number of ribs were preserved but have been omitted for clarity. Scale bar = 500 mm. Full size image 
 
 Unlike those of titanosaurs29,32, the dorsoventrally thin, but transversely broad, sternal plates (Fig. 4j) lack a reniform shape, although each sternal plate is approximately 70% the length of the humerus, a feature shared with other titanosaurs34. Relative to the long axis of the shaft, the distal end of the radius is bevelled at ~20° (Fig. 4k), and the mediolateral width of the proximal end of the radius is one-third its overall proximodistal length, characteristic of Titanosauria35. As is known for Diamantinasaurus22, and presumed in Wintonotitan33, the metacarpals are, from longest to shortest, III-II-I-IV-V, and manual phalanges were present on at least some of the digits. The maximum length of the longest metacarpal (Fig. 4l) is greater than 0.45 times that of the radius (0.49), a synapomorphy of Macronaria29, but this value is lower than in both Diamantinasaurus22 and Wintonotitan33. The distal condyle of metacarpal I is reduced, as in other Titanosauriformes29, and the distal end of metacarpal IV has an autapomorphic hourglass shape. 
 
 Both pubes and ischia are fused, forming a sheet-like structure over one metre wide at its narrowest point (Fig. 4n), and less than one centimetre thick at the junction of the four elements. An autapomorphic ridge extends anteroventrally from the ventral margin of the obturator foramen along the lateral surface of the pubis. The posterolateral process of the ischium is less-developed than in Wintonotitan33. Distally, the ischia are coplanar, and are significantly shorter than the pubes (ratio < 0.8), as in most somphospondylans27,34. As is typical for Neosauropoda29, the astragalus of Savannasaurus is wedge-shaped; however, its morphology differs markedly from that of Diamantinasaurus22 and, indeed other sauropods, in that it is proximodistally taller than either mediolaterally broad or anteroposteriorly long (Fig. 4m). 
 
 Titanosauria Bonaparte and Coria, 1993 
 
 Diamantinasaurus matildae Hocknull, White, Tischler, Cook, Calleja, Sloan and Elliott, 2009 
 
 Holotype (including paratypes from the same individual [marked with an asterisk]) 
 
 AODF 603: three partial cervical ribs; two incomplete dorsal vertebrae*; dorsal ribs; four coalesced sacral vertebrae with bases of two sacral processes*; two isolated sacral processes; right scapula; right coracoid*; right and left humeri; right ulna; right radius*; left metacarpal I; right metacarpals II–V; five manual phalanges; left ilium; right and left pubes; right and left ischia; right femur; right tibia; right fibula; right astragalus20,22. 
 
 Referred specimen 
 
 AODF 836: left squamosal; nearly complete braincase; right surangular; skull fragments; atlas-axis; five post-axial cervical vertebrae; three dorsal vertebrae; partial sacrum; dorsal ribs; right scapula; both iliac preacetabular processes; paired pubes and ischia; associated fragments (Fig. 5). 
 
 Figure 5: Diamantinasaurus matildae, referred specimen AODF 836. (a,b) Braincase (left lateral and caudal views). (c,d) endocranium (left lateral oblique and ventral views). (e) Axis (left lateral view). (f) Cervical vertebra III (left lateral view). Abbreviations: bt, basal tuber; cca, internal carotid artery; coch, cochlea; crb, cerebral hemisphere; crbl, cerebellum; dds, dorsal dural sinus; fm, foramen magnum; hfp, hypophyseal fossa placement; ioa, internal ophthalmic artery; jug, jugular vein; lbr, endosseous labyrinth; mf, metotic foramen; midb, midbrain; mo, medulla oblongata; nc, nuchal crest; occ, occipital condyle; ofb, olfactory bulb; oft, olfactory tract; pp, paroccipital process; II, optic tract; III, oculomotor nerve; IV, trochlear nerve; V, trigeminal nerve; V 1 , ophthalmic branch of the trigeminal nerve; V 2+3 , maxillo-mandibular branch of the trigeminal nerve; VI, abducens nerve; VII, facial nerve; IX, glossopharyngeal nerve; X, vagus nerve; XI, accessory nerve; XII, hypoglossal nerve? structure of unknown or disputable identity/placement. Scale bar = 100 mm. Full size image 
 
 Horizon and locality 
 
 Winton Formation (Cenomanian–early Turonian26); AODL 127 (the “Elliot site”), Belmont Station, Winton, Queensland, Australia. 
 
 Description of AODF 836 
 
 The frontal of Diamantinasaurus would have formed the anterior margin of the supratemporal fenestra, a feature shared with Saltasaurus36 and Rapetosaurus37, but not Nemegtosaurus38. A posteroventrally directed occipital condyle (Fig. 5a) and the extension of the paroccipital processes as distoventral prongs (Fig. 5b) are both features characteristic of titanosaurs29. The dorsoventral height of the supraoccipital is less than that of the foramen magnum, and the basal tubera are greater than 1.5 times the width of the occipital condyle, lacking a raised lip and diverging at less than 50°—these features are shared with saltasaurids (e.g. Saltasaurus36), but not with nemegtosaurids (e.g. Nemegtosaurus and Rapetosaurus38). The foramen on the posterior surface of the basal tubera is also present in most titanosauriforms, but is absent in Nemegtosaurus and Rapetosaurus38. As is also the case in derived titanosaurs39, the opening for cranial nerve VI does not penetrate the pituitary fossa (Fig. 5c). The external foramen for the internal carotid artery lies medial to the basipterygoid process (Fig. 5d), a characteristic only observed in derived titanosaurs39. 
 
 All preserved postaxial presacral vertebrae are opisthocoelous, and show a camellate internal tissue texture. Diamantinasaurus has an anteroposteriorly short axis (Fig. 5e), a feature previously suggested as characterizing Saltasauridae31. The prezygapophyses of each preserved anterior cervical vertebra project further anteriorly than the anterior condyle of the centrum (Fig. 5f), distinguishing Diamantinasaurus from Saltasaurus36 and Rapetosaurus37. As is also the case in the holotype of Diamantinasaurus22, the dorsal surfaces of the cervical ribs are not excavated. In the middle dorsal vertebrae, the postspinal lamina extends ventral to the neural spine. 
 
 The scapular glenoid is laterally bevelled, and a flattened surface posterior to the ventral triangular process is present (Fig. 6), as in the holotype of Diamantinasaurus22, but not Wintonotitan33. No fossa is present on the medial surface of the scapula, and the posterolateral process of the ischium is weak; both of these features distinguish Diamantinasaurus from Wintonotitan33. The pubes and ischia are robust, and the morphology of these elements far more closely approximates those of the Diamantinasaurus holotype33 than those of the Savannasaurus or Wintonotitan type specimens33. 
 
 Figure 6: Scapulae of Diamantinasaurus matildae. (a) Diamantinasaurus matildae holotype right scapula AODF 603 (right lateral view). (b) Diamantinasaurus matildae referred right scapula AODF 836 (right lateral view). Abbreviations: fs, flattened surface; vtp, ventral triangular process. Scale bar = 200 mm for (a) and 140 mm for (b). Full size image 
 
 Additional comparisons between Savannasaurus and Diamantinasaurus 
 
 The dorsal vertebrae of Savannasaurus and Diamantinasaurus are quite similar overall, but there are several differences. The type specimen of Diamantinasaurus includes two dorsal vertebrae22, one posterior (described as “dorsal vertebra A” by Poropat et al.22) and one anterior (“dorsal vertebra B”). Based on comparisons with Savannasaurus, the type anterior dorsal vertebra of Diamantinasaurus is Dv3, and its morphology is extremely similar to that of Savannasaurus. Both lack ventral keels, and both possess paired posterior centroparapophyseal laminae (PCPLs). However, the centroprezygapophyseal laminae (CPRLs) of Savannasaurus are paired, whereas those of Diamantinasaurus are not. Ventrally, the middle–posterior dorsal centra of both taxa are transversely concave, between ventrolateral ridges. However, the type posterior dorsal vertebra of Diamantinasaurus is quite different from the posterior dorsal vertebrae of Savannasaurus inasmuch as it possesses a ventral mid-line keel and has a vertical neural spine. In both taxa, the postspinal lamina extends ventral to the neural spine, beyond the postzygapophyseal articular surfaces. 
 
 The forelimbs of Savannasaurus are proportionally quite different from those of Diamantinasaurus. In Savannasaurus, the longest metacarpal (III) is 0.49 times the length of the radius, and the radius is less than 0.75 times the length of the humerus, whereas in Diamantinasaurus, the longest metacarpal (III) is 0.61 times the length of the radius, and the radius is 0.63 times the length of the humerus. The maximum diameter of the proximal end of the radius divided by the proximodistal length is 0.3 or greater in both taxa. 
 
 Perhaps the most notable differences between the two specimens lie in the pelvic girdle. Whereas the pubis and ischium of Diamantinasaurus are slightly proximodistally longer than those of Savannasaurus, the mediolateral width of the articulated pubes and ischia of the latter greatly exceeds that of the former (ratio of 1.2–1.4 depending on point of measurement). Thus, Savannasaurus must have been proportionally wider across the hips than Diamantinasaurus, which is corroborated by measurements of the sacral vertebrae. Both taxa share the presence of an anteriorly expanded ‘boot’27 at the distal end of the pubis. 
 
 Phylogenetic results 
 
 Following a priori pruning of ten unstable and highly incomplete taxa (see Supplementary Information), our equal weights analysis resulted in 12 MPTs of 1,508 steps and produced a largely resolved strict consensus tree (Supplementary Fig. S1), with polytomies restricted to: (1) a clade within Brachiosauridae; (2) the base of Titanosauria; and (3) several lithostrotian taxa outside of Saltasauridae. The agreement subtree (i.e. the largest fully resolved topology common to all MPTs) required the a posteriori pruning of four further taxa (Supplementary Fig. S2) and is shown in Fig. 7 as a time-calibrated phylogenetic tree, with basal nodes collapsed for simplicity. Bremer supports vary from 1 to 3 throughout the tree, with the best supported clades including Euhelopodidae and Lithostrotia. The tree topology is largely congruent with that presented in previous iterations of this data matrix22,23,27,33; consequently, we focus on the results pertaining to the Australian taxa. 
 
 Figure 7: Time-calibrated phylogenetic tree, with basal nodes collapsed for simplicity. (see Supplementary Fig. S2 for full version). The box next to each taxon demarcates its temporal range (including stratigraphic uncertainty), whereas the colour of the box reflects the continent(s) from which the taxon derives (light blue = North America; light green = Europe; red = Asia; dark blue = South America; yellow = Africa; purple = India; dark green = Australia). Full size image 
 
 Wintonotitan is recovered as a non-titanosaurian somphospondylan, just basal to the titanosaur radiation (Fig. 7), similar to its position in previous analyses of this data matrix22,27,33. Diamantinasaurus was recovered as an opisthocoelicaudine by Poropat et al.22; by contrast, it is resolved herein as a non-lithostrotian titanosaur (Fig. 7), forming the clade Savannasaurus + (Diamantinasaurus + AODF 836) (Bremer support = 2). Further results pertaining to Titanosauria, and those based on our implied weights analysis, are reported in the Supplementary Information and in Supplementary Figs S1–S8. 
 
 Palaeobiogeographic results 
 
 The results of our unconstrained BioGeoBEARS analyses (i.e. those that do not take palaeogeography into account) estimate Asia as being the sole area occupied by the most recent common ancestor (MRCA) of the Diamantinasaurus + Savannasaurus lineage and other titanosaurs, as well as the MRCA of Wintonotitan and other somphospondylans (Supplementary Table S26; Supplementary Figs S9–14). These results are consistent with previous suggestions that mid-Cretaceous Australian dinosaurian faunas are most similar to those of East Asia13,14, and that such faunas represent the product of direct trans-oceanic dispersal between these two regions40. The incorporation of palaeogeographic data in our analyses, however, has a marked effect on the inferred biogeographic history. In particular, the MRCAs of the two early Late Cretaceous Australian sauropod lineages are estimated to have occupied both Asia and South America minimally, and in several analyses these ancestral ranges also encompass Africa and Indo-Madagascar (Supplementary Table S26; Supplementary Figs S15–22). Moreover, when palaeogeographic data are included, the best-fitting maximum likelihood (ML) models are BAYAREALIKE and BAYAREALIKE + J (although DEC + J is also favoured in analyses where taxon midpoint ages are used to time-calibrate the tree, and constraints on intercontinental dispersal are more relaxed—see discussion in Supplementary Information for further details). BAYAREALIKE and BAYAREALIKE + J are ML models that exclude the possibility of vicariance41. Although it would be premature to rule out a role for vicariance in determining the palaeogeographic distributions of Cretaceous macronarians (see Supplementary Information), such a result does imply that the dominant biogeographic processes at work include dispersal, founder-event speciation, sympatry, and regional extinction.
– An Australian sheep farmer has discovered a beast far bigger than he's ever handled—along with new clues as to how dinosaurs ended up Down Under. Paleontologists, together with dinosaur enthusiast/sheep farmer David Elliot, say they've uncovered a new monster of a dinosaur belonging to the titanosaur subgroup of sauropods—long-necked herbivores like brontosaurus—which may have migrated to Australia from South America. Experts previously thought nearly all dinosaurs reached Australia through Asia, reports the Guardian. But one of the most complete sauropod skeletons ever found in Australia—pieced together after Elliot found a toe bone on his Queensland property about a decade ago—says otherwise. Elliot found fossils from another known sauropod species as well; it and the Savannasaurus elliottorum allowed paleontologists to complete an evolutionary analysis that suggests Australia's sauropods descended from dinosaurs in South America and must've crossed Antarctica during a warm spell 105 million to 100 million years ago, per National Geographic. As for the defining characteristics of the 20-foot-tall, 50-foot-long Savannasaurus, which roamed some 95 million years ago: Stephen Poropat, lead author of the report on the find in Scientific Reports, describes the 20-ton beast as "a long-necked, long-legged hippo" with wide hips, some unusually "paper-thin" bones in its pelvis, and a huge belly. (It also might have cooed.)