Cruxicheiros

What is Cruxicheiros?

Cruxicheiros is a genus of theropod dinosaur that lived during the Middle Jurassic period, approximately 167 million years ago. Its fossils were discovered in England, and the genus name, "Cruxicheiros," translates to "cross hand," a nod to the "Cross Hands Quarry" where the remains were found. The type species, Cruxicheiros newmanorum, was formally described in 2010.

Discovery and Classification

The holotype fossil of Cruxicheiros was unearthed in the early 1960s in the Cross Hands Quarry, Warwickshire. These fossils originate from the Chipping Norton Limestone Formation, dating to the lower Bathonian stage of the Middle Jurassic. The transfer of these previously overlooked fossils to the Warwickshire Museum Service in 2008 prompted their closer examination, leading to their recognition as a distinct genus.

Cruxicheiros is classified as a tetanuran, a broad group of theropod dinosaurs that also includes iconic predators like Tyrannosaurus and Spinosaurus, as well as the ancestors of birds. However, its precise placement within Tetanurae remains uncertain. Cladistic analyses have presented multiple equally probable evolutionary positions for Cruxicheiros, leading to its classification as Tetanurae incertae sedis (of uncertain placement).

Physical Characteristics and Size

Based on the limited fossil evidence, Cruxicheiros is understood to have been a large theropod. Thomas Holtz estimated its length at approximately 9 meters (29.5 feet). The known material includes a partial right femur, vertebrae, a scapulocoracoid, an ilium, a pubis, and bone fragments. Differences in its leg and hip bones, as well as its lower and broader dorsal spines, distinguish it from other theropods found in the same formations, such as Megalosaurus.