Dracoraptor

Dracoraptor is a genus of carnivorous neotheropod dinosaur from the Hettangian age of the Early Jurassic period of Wales.

Discovery
The Dracoraptor fossils were discovered in 2014 and 2015 near the Welsh town of Penarth. In March 2014, brothers and amateur paleontologists Nick and Rob Hanigan, while searching for ichthyosaur remains at Lavernock Point, the large cape south of Cardiff, found stone plates containing dinosaur fossils, fallen off the seven metres high cliff face. Judith Adams and Philip Manning of the University of Manchester made X-ray pictures and CAT-scans of the fossils. The remains were donated to the Amgueddfa Cymru – National Museum Wales. They were prepared by Craig Chivers en Gary Blackwell. On 20 July 2015, student Sam Davies found additional plates with foot bones.[1]

The type species, Dracoraptor hanigani, was named and described in 2016 by David M. Martill, Steven U. Vidovic, Cindy Howells, and John R. Nudds. The generic name combines the Latin draco, "dragon", a reference to the Welsh Dragon, with raptor, "robber", a usual suffix in the names of theropods. The genus name was suggested by the Hanigan brothers. The specific name honours Nick and Rob Hanigan as discoverers although to be grammatically correct it should be haniganorum.[1]

The holotype, NMW 2015.5G.1–2015.5G.11, was discovered in the lower Bull Cliff Member of the Blue Lias Formation in the United Kingdom. More precisely, it came from a layer just meters below the first occurrence of Jurassic ammonite Psiloceras and above the Paper Shales that represent the lithological Triassic-Jurassic boundary, precisely dating the dinosaur to the earliest Hettangian, 201.3 million years ago ± 0.2 million years.[1]

The holotype consists of a partial skeleton with skull. It contains both praemaxillae, both maxillae, teeth, a lacrimal, a jugal, a postorbital, een squamosal, a supraoccipital, parts of the lower jaws, a possible hyoid, two neck vertebrae, neck ribs, rear back vertebrae, at least five front tail vertebrae, chevrons, ribs, belly ribs, the lower parts of a left forelimb, a furcula, both pubic bones, a left ischium, a right thighbone, a shinbone, the upper part of a calf bone, a left astragalus, three tarsals and three metatarsals. About 40% of the skeletal elements is presented. Some bones have been preserved as natural moulds. The specimen in 2016 represented the most complete Mesozoic theropod known from Wales.

Size and distinguishing traits
Dracoraptor was a biped, much like its relatives. The fossil discovered in Wales is a 7-foot-long (2.1 metre) juvenile with a hip height of seventy centimetres; adults may have been ten feet (three meters) long.

In 2016, some distinguishing traits were established. The praemaxilla carries only three teeth, a basal trait. The jugal has a thin front branch running to the maxilla. The bony external nostril is large and has a thin branch beneath it. The pubic bone is obliquely directed to the front and is considerably longer than the ischium. The fourth tarsal has a process at the upper side.

Skeleton
In the front of the snout each praemaxilla embraces the front of a very large nostril. The skull bears three premaxillary teeth per side and at least seven maxillary teeth. The teeth are recurved or dagger-shaped. The edges of the tooth crown are serrated with six to eight denticles per millimetre. On the trailing edge these serrations run all the way to the root, on the leading edge they end at a higher position. Towards the tip of the tooth, these denticles become gradually somewhat smaller. The maxilla borders an antorbital fenestra with a shallow depression. The jugal is a slender element with a straight lower edge, a thin front branch overlapped by the rear branch of the maxilla and an ascending process towards the lacrimal that is thin but not pointed. The lacrimal is rectangular and pinched in the middle.

The neck vertebrae are elongated, opisthocoelous, i.e. with a vertebral body that is convex in front and concave at the rear, and crowned by low neural spines. Their undersides are slightly convex and their cross-sections are rectangular. At the front side the vertebral body is pierced by a pleurocoel, a depression with a pneumatic opening for the air sac to enter the inside of the vertebra. The [[tail] vertebrae have two parallel keels at their undersides, which peter out towards the front. Their side processes are flat and broad.[1]

The presence of a furcula was reported. Furculae have only rarely been recovered from early theropod fossils; other examples include those of Segisaurus and Coelophysis. The lower arm bones, the ulna and the radius, have a length of about seven centimetres. Hand elements are present but a formula of the phalanges could not determined.[1]

In the pelvis, the pubic bone has a length of 212 millimetres. It points obliquely to the front. The pubic foot is moderately broadened in side view, bot at the front and at the rear. The shaft of the ischium is with a length of 129 millimetres markedly shorter than the pubic shaft. On the upper front edge a rectangular obturator process is present, forming a clear obturator notch with the ischial shaft. The shaft fan out to below, into an ischial foot.[1]

On the thighbone, the lesser trochanter has about two thirds of the height of the greater trochanter and is separated from it by a V-shaped cleft. A clear fourth trochanter is present. In the foot, the third metatarsal has a length of 116 millimetres.