Cruxicheiros: dinosaurs of the infraorder tetanura

Cruxicheiros is a genus of dinosaurs of the Tetanurae infraorder of the theropod suborder that lived in the Middle Jurassic period in England. Represented by the only species Cruxicheiros newmanorum, which was described in 2010 by paleontologists Roger Benson and Jonathan Radley.

The Greek-Latin name Cruxicheiros is a literal translation of the English place name Cross Hands and means “crosshand lizard”.

Fossil remains of the holotype Cruxicheiros newmanorum were discovered in the early 1960s at the Cross Hands quarry, located near the town of Little Compton in Warwickshire, England. They were recovered from the Chipping Norton limestone formation, which is about 167 million years old in the Lower Bathonian substage of the Middle Jurassic period.

Until 2008, the dinosaur bones were kept in the Birmingham Museum and Art Gallery, and then were transferred to the Warwickshire Museum Society (Warwickshire Museum Service); this transmission contributed to a more detailed study of the almost forgotten remains.

Dating back to at least 1677, a number of unidentified dinosaur bones have been discovered in England, many of which are theropods. At the same time, the largest fossil remains were attributed (without critical consideration) to Megalosaurus, and the smaller ones to Iliosuchus.

A 2010 description acknowledges differences between the Crosshand find and the bones attributed to Megalosaurus in terms of the height and width of the spine and the shape and size of the hip bones. R. Benson and J. Radley named the Crosshand holotype Cruxicheiros newmanorum; while the specific name newmanorum was given in honor of the Newman family, which is the owner of the Cross Hands quarry.

Cruxicheiros was a large theropod, but the available bone material is insufficient to accurately determine its size. The holotype, which has been assigned the WARMS catalog number G15770, is part of the right femur.

Additional bone material found at the same site probably belongs to the same dinosaur specimen as the holotype, judging by the fact that the rock in which all the bones were enclosed is composed of sandy limestone and calcite. Additional material includes an anterior thoracic or posterior cervical vertebra; neural arc; part of the thoracic vertebra; anterior half of the mid-distal caudal vertebra; part of the right scapulocoracoid; part of the left iliac bone; proximal end of the left pubic bone; as well as many fragments of ribs and bones.

Cruxicheiros belongs to the infraorder Tetanura, which also includes theropods such as Tyrannosaurus and Spinosaurus. The compilers of the description did not attribute Cruxicheiros to any order. They conducted a cladistic analysis, which identified 3 equally likely positions for it in the classification:

  • 1) as the oldest genus of the Neotetanura order (from which dinosaurs such as the Allosaurus and birds originated),
  • 2) as the oldest genus of the order Megalosauroids (from which Megalosaurus and Spinosaurus originated), or
  • 3) as the oldest genus of the tetanura infraorder, the very first representatives of which appeared presumably even before the separation of these theropod orders.
  • Given the ambiguous findings, Benson and Radley classified Cruxicheiros as a taxon with an indeterminate position in the infraorder Tetanurae (Tetanurae incertae sedis).

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