Cumnoria

What is Cumnoria?

Cumnoria is a genus of basal iguanodontian dinosaur that inhabited what is now the United Kingdom during the Late Jurassic period, specifically the Kimmeridgian age. The holotype specimen, found in Oxfordshire, represents a juvenile individual estimated to be about 3.5 meters (11.4 feet) long and possessed a slender, bipedal build.

Discovery and Classification

Fossils of Cumnoria were discovered at the Chawley Brick Pits in Cumnor Hurst, Oxfordshire. Initially, these remains were reported as a new species of Iguanodon and later named Iguanodon prestwichii by John Whitaker Hulke. In 1888, Harry Govier Seeley established the new genus Cumnoria after the village of Cumnor. However, its classification has been debated; it was later assigned to Camptosaurus for over a century before modern analyses by David Norman, Darren Naish, and David Martill, and Andrew T. McDonald reaffirmed its distinct generic status. While some studies have synonymized it with Camptosaurus, recent work continues to support its separation as a unique genus, potentially representing the oldest known styracostern.

Physical Characteristics

Cumnoria is distinguished by several anatomical features, particularly in its shoulder girdle and teeth. The holotype, being a juvenile, exhibits a lack of fusion in its vertebrae and ribs. Notable characteristics include a prominent ridge on the sternal process of the coracoid and an oval muscle scar on the humerus. Uniquely among non-hadrosauriforms, its scapula shows moderately diverging margins, and its dentary teeth lack a defined cingulum.