Spinosaurus | History of Discovery

Naming

Two species of Spinosaurus have been named: Spinosaurus aegyptiacus (meaning "Egyptian spine lizard") and the disputed Spinosaurus maroccanus (meaning "Moroccan spine lizard").[20][21]

The first described remains of Spinosaurus were found and described in the early 20th century. In 1912, Richard Markgraf discovered a partial skeleton of a dinosaur in the Bahariya Formation of western Egypt. In 1915, German paleontologist Ernst Stromer published an article assigning the specimen to a new genus and species Spinosaurus aegyptiacus.[19][20]

Fragmentary additional remains from Bahariya, including vertebrae and hindlimb bones, were designated by Stromer as "Spinosaurus B" in 1934.[22] Stromer considered them different enough to belong to another species, and this has been borne out. With the advantage of more expeditions and material, it appears that they pertain either to Carcharodontosaurus[23] or to Sigilmassasaurus.[21]

S. maroccanus was originally described by Dale Russell in 1996 as a new species based on the length of its neck vertebrae.[21] Specifically, Russell claimed that the ratio of the length of the centrum (body of vertebra) to the height of the posterior articular facet was 1.1 in S. aegyptiacus and 1.5 in S. maroccanus.[21] Later authors have been split on this topic. Some authors note that the length of the vertebrae can vary from individual to individual, that the holotype specimen was destroyed and thus cannot be compared directly with the S. maroccanus specimen, and that it is unknown which cervical vertebrae the S. maroccanus specimens represent. Therefore, though some have retained the species as valid without much comment,[24][25][26] most researchers regard S. maroccanus as a nomen dubium[4][27][28] or as a junior synonym of S. aegyptiacus.[23]

Specimen

BSP 1912 VIII 19

BSP 1912 VIII 19, described by Stromer in 1915 from the Bahariya Formation, was the holotype.[19][20] The material consisted of the following items, most of which were incomplete: right and left dentaries and splenials from the lower jaw measuring 75 centimeters (30 in) long; a straight piece of the left maxilla that was described but not drawn; 20 teeth; 2 cervical vertebrae; 7 dorsal (trunk) vertebrae; 3 sacral vertebrae; 1 caudal vertebra; 4 thoracic ribs; and gastralia.[19] Of the nine neural spines whose heights are given, the longest ("i," associated with a dorsal vertebra) was 1.65 meters (5.4 ft) in length.[19] Stromer claimed that the specimen was from the early Cenomanian, about 97 million years ago.
NMC 50791

NMC 50791, held by the Canadian Museum of Nature, is a mid-cervical vertebra which is 19.5 centimeters (7.7 in) long from the Kem Kem Beds of Morocco.[21] It is the holotype of Spinosaurus maroccanus as described by Russell in 1996.[21] Other specimens referred to S. maroccanus in the same paper were two other mid-cervical vertebrae (NMC 41768 and NMC 50790), an anterior dentary fragment (NMC 50832), a mid-dentary fragment (NMC 50833), and an anterior dorsal neural arch (NMC 50813).[21] Russell stated that "only general locality information could be provided" for the specimen, and therefore it could be dated only "possibly" to the Albian.
MNHN SAM 124

MNHN SAM 124, housed at the Muséum National d'Histoire Naturelle, is a snout (consisting of partial premaxillae, partial maxillae, vomers, and a dentary fragment).[29] Described by Taquet and Russell in 1998, the specimen is 13.4 to 13.6 centimeters (5.3–5.4 in) in width; no length was stated.[29] The specimen was located in Algeria, and "is of Albian age."[29] Taquet and Russell believed that this specimen along with a premaxilla fragment (SAM 125), two cervical vertebrae (SAM 126-127), and a dorsal neural arch (SAM 128), belonged to S. maroccanus.
MSNM V4047

MSNM V4047 (in the Museo di Storia Naturale di Milano), described by Dal Sasso and colleagues in 2005, consists of a snout (premaxillae, partial maxillae, and partial nasals) 98.8 centimetres (38.9 in) long from the Kem Kem Beds.[4] Like UCPC-2, it is thought to have come from the early Cenomanian. Arden and colleagues in 2018 tentatively assigned this specimen to Sigilmassasaurus brevicollis given its size. In the absence of associated material, however, it is difficult to be certain which material belongs to which taxon.

Naming

Specimen

BSP 1912 VIII 19

NMC 50791

MNHN SAM 124

MSNM V4047