Spinosauridae

Spinosauridae

This group is one of the most representative in the Kem Kem Group fossil record; however, the nature of the material is isolated or semi-articulated fossils. Two partial dentaries from south-eastern Morocco were described by Buffetaut (1989), being both referred to Spinosaurus cf. Sp. aegyptiacus . Based on a set of isolated bones, including cervical vertebrae, dorsal neural arch, and a fragmentary dentary recovered from Morocco, Russell (1996) erected the name Spinosaurus maroccanus ; later on, Taquet and Russell (1998) referred a rostrum and some axial elements recovered from the Algerian portion of the Sahara Desert to this species. However, this species is frequently regarded as a nomen dubium (e.g. Carrano et al. 2012), a junior synonym of Spinosaurus aegyptiacus (e.g. Ibrahim et al. 2014a), or Spinosaurinae indet. (e.g. Lacerda et al. 2022). Milner (2003) presented a rostrum and a relatively well-preserved dentary from Morocco in a brief note; both of them were referred to Sp. aegyptiacus . This rostrum is redescribed in detail in this work (NHMUK PV R 16420) and considered as an indeterminate Spinosaurinae , agreeing with the current debate (e.g. Sales and Schultz 2017, Lacerda et al. 2022). Another rostrum, which represents the most complete and well-preserved known to date, and a pair of nasals from Morocco were described by Dal Sasso et al. (2005), with both referred to Spinosauru s cf. Sp. aegyptiacus . Lately, some studies (e.g. Sales and Schultz 2017, Lakin and Longrich 2019, Lacerda et al. 2022) have argued that the most reliable identification of that rostrum is Spinosaurinae indet. due to a lack of overlap between these specimens and the Sp. aegyptiacus holotype. Based on several skeletal elements of a subadult individual, Ibrahim et al. (2014a) proposed a neotype to Sp. aegyptiacus , and later on, new skeletal remains possibly of the same individual represented by a robust tail were also recovered from Morocco ( Ibrahim et al. 2020a). Two morphotypes of spinosaurids, Sp. aegyptiacus and cf. Sigilmassasaurus brevicollis , were identified by Hendrickx et al. (2016) based on six quadrates that probably derived from Morocco. A tiny pedal ungual recovered from between the villages of Taouz and Begaa was presented by Maganuco and Dal Sasso (2018). Arden et al. (2019) also described two morphotypes of spinosaurids from the Kem Kem Group: one referred to Sp. cf. Sp. aegyptiacus based on frontals and a frontoparietal, and a skull roof referred to Sigilmassasaurus cf. Si. brevicollis . Based on cranial remains and isolated axial elements, Lakin and Longrich (2019) also described fossils referred to Si. brevicollis and Sp. cf. Sp. aegyptiacus . Besides the previous mentions, other studies also described axial elements of Sigilmassasaurus brevicollis recovered from the same region (e.g. Russell 1996, McFeeters et al. 2013, Evers et al. 2015).

In this contribution we have described several specimens that expand the knowledge of occurrences of spinosaurids in the Kem Kem Group. Among these, we have presented a cervical vertebra referred to Si. brevicollis (NHMUK PV R 38358), in addition to nine specimens (NHMUK PV R 16391, 16422, 16423, 16424, 16426, 16430, 16431, 16433, 16438) that we conservatively classified as indeterminate Spinosaurinae . Our findings, combined with materials mentioned above, contribute to general aspects of the occurrence of spinosaurids in the region, making them one of the most abundant groups of theropod dinosaurs in the Kem Kem Group.