HMN 2025: How Velociraptorine fossil with unusually robust arms suggests a brand new predatory area of interest

An worldwide group of paleontologists led by the University of Poitiers, France, report {that a} just lately recovered velociraptorine fossil, Shri rapax, brandished unusually massive, highly effective clawed arms. Findings mark to an evolutionary area of interest inside Mongolia’s Late Cretaceous desert fauna.

Research on dromaeosauridae, small to medium-sized feathered carnivores, usually focuses on their strong foot claws. Previous descriptions of Velociraptor mongoliensis and associated dromaeosaurids documented proportionally slender hand digits, in distinction to the enlarged hand morphology noticed in Shri rapax.

In the review, “A brand new bird-like dinosaur from the Upper Cretaceous of Mongolia with extraordinarily strong arms helps area of interest partitioning amongst velociraptorines,” published in Historical Biology, researchers described a virtually full skeleton from totally different sources to evaluate whether or not hand type signaled a definite predatory technique.

Provenance of the Shri rapax specimen is clouded by black market poaching that occurred someday earlier than 2010, sending it to non-public collections in Japan and later England. The cranium and first 4 cervical vertebrae had been separated and scanned in 2016 on the Royal Belgian Institute of Natural Sciences (RBINS), after which they had been returned to the proprietor. The present location of those supplies stays unknown.

The remainder of the skeleton, 23 tail vertebrae, an intact manus (hand) and most main girdle parts (shoulder and pelvic bones), was obtained by the French firm Eldonia and later repatriated to Mongolia. A solid of the lacking cranial parts, printed from the 2016 scan knowledge, now accompanies the unique mounted specimen.

Preparation and consolidation work carried out at RBINS revealed beforehand unexposed anatomy, together with the suitable arm and left pelvic bones. The specimen, now housed on the Institute of Paleontology and Geology in Ulaanbaatar as MPC-D 102/117, was seemingly recovered from the Djadokhta Formation in Mongolia primarily based on its sediment matrix, although its exact locality stays unsure.

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

Morphometric and cladistic analyses positioned Shri rapax as sister to the Baruungoyot-formation species Shri devi, with divergence in 10 post-cranial traits, together with a 135° opisthopubic pubis (backward-angled hip bone), an ischium 66% of pubic size (decrease rear hip section), and absence of ischial tuberosity (bony hip projection). Enlarged hand construction implies prey dealing with forces exceeding these inferred for Velociraptor, whereas cranium measurements point out a stronger chew.

Researchers conclude that outsized arms and stout jaws let Shri rapax deal with burlier prey, probably grownup protoceratopsians or juvenile ankylosaurs, lowering competitors of dietary overlap with different velociraptorines.

Broader prey partitioning amongst predators helps clarify the unexpectedly wealthy dromaeosaurid range preserved in Gobi Desert dune fields, illuminating how Mesozoic meals webs balanced competitors by prey specialization.

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