Etymology: Sickle reptile; referred to the big claws brought by the second digits of the hands
Systematic Palaeontology: Reptilia; Diapsida, Drepanosauridae
Distribution: Upper strata of the Calcari di Zorzino (Norian Age)
Locality: Endenna (Bergamo, Lombardy, Northern Italy)
Repository: Museo Civico di Scienze Naturali "Caffi" di Bergamo
Drepanosaurus is a medium sized reptile (the only known specimen being 40 cm. in length excluding the head and the neck) with a barrel-shaped trunk and a leaf-like tail. The neural spines of the first five dorsal vertebrae are distally expanded, forming a functional unit; the pre- and postzygapophises are straight and horizontally directed; the caudal vertebrae are somewhat longer than the more posterior dorsal and sacral ones, bearing tall, narrow neural spines slightly expanded distally and deep narrow, anteriorly bent haemapophisys. The haemapophisys of the anterior portion of the tail are attached to the posterior rim of the ventral margin of the centrum, those of the posterior portion of the tail are attached to the anterior rim of the ventral margin of the centrum; last two caudal vertebrae are modified to a sharp, hooked spine.
The shoulder girdle consists of a very tall a narrow scapula and a small rounded coracoid. The pelvic girdle consists of a tall, wide ilium, gently bent cranially, and a large puboischiadic plate with a thyroid fenestra that does not reach the symphysis. In the anterior limb a wide flat bone, contacting both the humerus and the proximal head of the radius, is considered as an expanded ulna. The phalangeal formula for the manus is 2?,2,2,2,2; metacarpals and phalanges are long and strong; the last phalanx bears a sharp hooked claw; the claws of the second digit are very long and wide, as high as the shaft of the radius. The phalangeal formula for the pes is 2,3,3,3,3; the fifth metatarsal is not hooked; the phalanges are long, strong and bear long, strong and hooked claws.
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