On evidence of a bird from the Wealden beds of Ansty Lane, near Cuckfield / by H.G. Seeley.

  • Seeley, H. G. (Harry Govier), 1839-1909.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: On evidence of a bird from the Wealden beds of Ansty Lane, near Cuckfield / by H.G. Seeley. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Lf-Z On Evidence of a Bird from the Weald en Beds of Ansty Lane, near Cuckfield. By Prof. H. G. Seeley, F.R.S., F.L.S., F.G.S. On a visit to Ansty Cross made by the London Geological Field Class, I identified a fragment of bone found embedded in the sand- stone by Mr. Neville Jones, as probably the distal end of the femur of a bird. It was unfortunately extracted from the matrix, and subsequently it was left with me for determination. The fragment is f inch long, compressed from back to front, with the bone of the shaft thick and enclosing a small medullary cavity. At the proximal fracture the bone is 5 inch wide and 1- inch thick. The width at the distal articulation is ^ inch ; and the bone becomes bent downward and is thickened inferiorly with develop- ment of the condyles, though not to quite the extent seen in most existing birds. The inner side of the bone is narrower than the outer side. As the narrow, rounded inner side of the shaft is prolonged distally, it becomes flattened, with a slight median convexity; and is thickened, partly owing to a superior marginal ridge, and partly in consequence of the thickening of the inner condyle. The outer side of the bone is thicker, but not so thick as in the femur of Enaliornis; nor is the external side flattened so much as in that genus. An inflation on its middle part defines a superior lateral oblique area, below which there is an imperfect groove. This defines a thickening of the outer side of the large external condyle, quite on the type of Enaliornis and Colymbus. The external condyle is not only larger and deeper, but is more prolonged distally. This is perhaps the most distinctive avian character ; for though in a Dinosaur the inner side of the distal end may bo flattened, and the outer side angular, it is the inner condyle which is usually the larger. And in no case is the external condyle produced distally, except apparently in Hypsilophoclon, exceptionally according to Hulke’s figure. The condyles are well rounded. The external surface of the bone, in consequence of the size of the outer condyle, has the appearance of extending obliquely outward, making a slight approximation to the condition seen in Colymbus and its allies. The superior surface of the bone does not widen so rapidly at the distal articulation as in Enaliornis ; but there is a similar shallow groove on it which widens to the distal extremity, extending later- ally over the condyles. The groove becomes prolonged into the notch between the condyles on the distal extremity of the bone. The inferior surface of the shaft is concave in length and also from side to side, being bounded laterally by slightly-developed rounded ridges, which extend proximally from the condyles. The notch between the condyles is narrower and deeper than in Enali- ornis, owing chiefly to the well-rounded form of the condylar surfaces on the under side of the bone.