Paluxysaurus jonesi hi-fi skeletals

The two main individuals known from Paluxysaurus jonesi (there are several others which have not been photographed/published). This was a tough skeletal due to the lack of photo references for much of the catalogued material, and due to the FWMSH material being split up piecemeal into many specimen numbers irrespective of which individual skeleton the bones came from. The holotype is just the nasal and maxilla, though most of the material figured here for the FWMSH specimens is likely from the same individual. The TMM museum, for their part, at least used the same specimen number for all the bones from its lone individual skeleton. More museums should do that, it makes things SO much easier.

Paluxysaurus jonesi

Family: Chubutisauridae (basal Somphospondyli)
Time: Early Cretaceous, Albian epoch, ~110 mya
Location: Twin Mountains formation, Trinity group, Jones Ranch, Texas, USA

The larger individual (TMM 42488) probably massed around 17 tons and appears to be mature or close to it. Adult Paluxysaurus were therefore too big for Deinonychus and even Utahraptor to tackle (unless it was a pack of them), but still within range of Acrocanthosaurus' menu.

This is the best-known of the Early Cretaceous titanosauriforms from Texas. It was closely related to the much larger Sauroposeidon, but contra D'Emic and Foreman (2012) appears to be a different genus due to variations in the laminae, the size and spacing of various processes in the dorsals, and the TMM specimen having a mostly fused coracoid (and thus indicating Paluxysaurus reached maturity at a much smaller size).

What is more certain from D'Emic and Foreman's research, for both animals, is that they are clearly more derived than the brachiosauridae, and their unique twisted interlock of the radius and ulna, widely spaced prezygapophyses, small centrum and higher neural arches, distal taper to the femur, and other unique traits put them firmly in a clade with Chubutisaurus and its odd tall-spined cousin Ligabuesaurus, and the similarity of the Paluxysaurus skull material to Sarmientosaurus indicates it was also a chubutisaurid. "Angloposeidon" as well as the excellent Wealden pelvic material figured in Blows (1995) are likely also chubutisaurs, and the colossal French Monster is a strong candidate for this family as well: paleoking.blogspot.com/2014/07… , having a nearly identical in situ femur shape to Paluxysaurus, which shows no signs of gaps or displacement of fragments. The Chubutisauridae appear to be a couple of nodes more derived than brachiosaurs, with the "Laurasiformes" such as Tastavinsaurus, Venenosaurus, and possibly Astrophocaudia forming an intermediate clade between the two groups.

From the outside they still looked superficially like brachiosaurs, though with a more compact nose and a more gradual taper to the tail, and going by the Paluxy river footprints (likely made by Sauroposeidon), they also had a 4th toe claw on the foot, a feature not found in either brachiosaurs or titanosaurs (though a trackway in China's Gansu province indicates it may also be present in Huanghetitan). The odd dip in the tail is natural (in fact, I have relaxed it somewhat here). The kink in the femur is also a natural feature, one that is not found in some other chubutisaurs, but oddly enough was re-evolved in more derived somphospondyls like Euhelopus, Daxiatitan and Janenschia. At some point I plan to do a skeletal of the juvenile Sauroposeidon material from the Cloverly formation in Montana, and see how it comes out (even as a juvenile, Sauroposeidon had a more robust femur and more pronounced laminae than Paluxysaurus, and there are proportional differences in the dorsals and caudals too).


REFERENCES:

Rose, Peter J. (2007). "A new titanosauriform sauropod (Dinosauria: Saurischia) from the Early Cretaceous of central Texas and its phylogenetic relationships" (web pages). Palaeontologia Electronica. 10 (2).

D'Emic, M.D.; Foreman, B.Z. (2012). "The beginning of the sauropod dinosaur hiatus in North America: insights from the Lower Cretaceous Cloverly Formation of Wyoming". Journal of Vertebrate Paleontology. 32 (4): 883–902.