糖心视频

An international group of paleontologists led by the University of Poitiers, France, report that a recently recovered velociraptorine fossil, Shri rapax, brandished unusually large, powerful clawed hands. Findings point to an evolutionary niche within Mongolia's Late Cretaceous desert fauna.

Research on dromaeosauridae, small to medium-sized feathered carnivores, typically focuses on their robust foot claws. Previous descriptions of Velociraptor mongoliensis and related dromaeosaurids documented proportionally slender hand digits, in contrast to the enlarged hand morphology observed in Shri rapax.

In the study, "A new bird-like dinosaur from the Upper Cretaceous of Mongolia with extremely robust hands supports niche partitioning among velociraptorines," in Historical Biology, researchers described a nearly complete skeleton from different sources to assess whether hand form signaled a distinct predatory strategy.

Provenance of the Shri rapax specimen is clouded by black market poaching that occurred sometime before 2010, sending it to private collections in Japan and later England. The skull and first four cervical vertebrae were separated and scanned in 2016 at the Royal Belgian Institute of Natural Sciences (RBINS), after which they were returned to the owner. The current location of these materials remains unknown.

The rest of the skeleton, 23 tail vertebrae, an intact manus (hand) and most major girdle elements (shoulder and pelvic bones), was obtained by the French company Eldonia and later repatriated to Mongolia. A cast of the missing cranial elements, printed from the 2016 scan data, now accompanies the original mounted specimen.

Preparation and consolidation work conducted at RBINS revealed previously unexposed anatomy, including the right arm and left pelvic bones. The specimen, now housed at the Institute of Paleontology and Geology in Ulaanbaatar as MPC-D 102/117, was likely recovered from the Djadokhta Formation in Mongolia based on its sediment matrix, though its precise locality remains uncertain.

Computed-tomography and photogrammetric modeling captured cranial sutures (skull bone joints), double pleurocoels (air-filled cavities) in the first two dorsal centra (vertebrae near the shoulders), trapezoid deltopectoral crests (muscle attachment ridges on the upper arm), and a pollex ungual (thumb claw) 162% the length of its preceding phalanx, making digit I broader than digits II + III combined.

Morphometric and cladistic analyses placed Shri rapax as sister to the Baruungoyot-formation species Shri devi, with divergence in 10 post-cranial traits, including a 135掳 opisthopubic pubis (backward-angled hip bone), an ischium 66% of pubic length (lower rear hip segment), and absence of ischial tuberosity (bony hip projection). Enlarged hand structure implies prey handling forces exceeding those inferred for Velociraptor, while skull measurements indicate a stronger bite.

Researchers conclude that oversized hands and stout jaws let Shri rapax tackle burlier prey, possibly adult protoceratopsians or juvenile ankylosaurs, reducing competition of dietary overlap with other velociraptorines.

Broader prey partitioning among predators helps explain the unexpectedly rich dromaeosaurid diversity preserved in Gobi Desert dune fields, illuminating how Mesozoic food webs balanced competition through prey specialization.

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