Rugops

Rugops Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Restored skull
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Abelisauridae
Genus:	†Rugops Sereno et al. 2004
Species:	†R. primus
Binomial name
†Rugops primus Sereno et al. 2004

Rugops (meaning ‘wrinkle face’) is a

A skull pertaining to an

The generic name, Rugops, is derived from the Latin word "ruga" (wrinkle) and the Greek word "opsi" (face). The specific name is derived from the Latin word "primus" (first). Both the generic and specific name refer to Rugops as being one of the earliest abelisaurids with a textured skull.^[1]

In 2005, a partial right maxilla of an abelisaurid was described from the Kem Kem Group of Morocco. The maxilla shares some similarities with Rugops such as with the morphology of the teeth, the shape of the alveolar, the rugose texture on the lateral sides, the straight border with the premaxilla, and the position of the palatal shelf.^[7] However, the maxilla cannot be referred to Rugops as the diagnostic features of the genus are located on different parts of the skull.^[8]

Description

In 2010, Sereno gave Rugops an estimated length of 6 metres (19.7 ft) and weight of 750 kilograms (1,650 lbs).^[9] However, Grillo & Delcourt (2016) gave a lower estimate of 4.4 metres (14.4 ft) long while Molina-Pérez & Larramendi (2016) gave an estimate of 5.3 metres (17.4 ft) long and 410 kilograms (900 lbs) in weight.^[10][11]

Skull

The skull length of Rugops was about 31.5 centimetres (12.4 inches).

A maxilla (NPSJB-PV247) from Patagonia shows similarities with Rugops as the pattern of external ornamentation is nearly identical and the internal details are also have a close similarity.^[13][1] In Rugops, the interdenticular sulci of the denticles, the presence of which might possible be a synapomorphic characteristic of Abelisauridae, is absent and has a higher dental formulae than in any other abelisaurid.^[14] The nasal sculpturing of Rugops is similar to the ornamentation seen in Skorpiovenator as the surface of the nasals show hummocky-like rugosities and has grooves that lead into each foramen. However, unlike Skorpiovenator, Rugops lacks extra foramina on the skull roof that could represent homologues. The external morphology of the nasals are similar to that of Skorpiovenator as they share a similar foramina pattern. The ventral surface of the nasals have a series of foramina, which has been suggested to connect to an internal system.^[15]

The describing authors indicated two distinguishing traits. Both of these are autapomorphies, unique derived characters. The skull roof has small fenestra that are present between the prefrontal, frontal, post-orbital and lacrimal. The dorsal surface of each nasal has a row of seven small depressions.^[1]

Classification

Sereno et al. (2004) initially found Rugops to be the basalmost abelisaurid,^[1] a position also recovered by various analyses by Egli et al. (2016),^[16] Delcourt (2018),^[12] Cerroni et al. (2020)^[17] and Rolando et al. (2020).^[18] However, Rugops has also been recovered as being more derived than Rahiolisaurus and/or Eoabelisaurus but more basal than other abelisaurids by Pol & Rauhut (2012),^[19] Rauhut & Carrano (2016),^[20] and Iori et al. (2021).^[21] Other alternative positions include Rugops being more derived than Kryptops, Chenanisaurus and/or Spectrovenator as recovered by Sereno & Brusatte (2008),^[22] Zaher et al. (2020),^[23] Gianechini et al. (2021)^[24] and Agnolín et al. (2022),^[25] and within a polytomy with other abelisaurids such as Xenotarsosaurus, Tarascosaurus, Ilokelesia and Genusaurus which has been recovered by Tortosa et al. (2014),^[26] Baiano et al. (2020)^[27] and Salem et al. (2022).^[28]

A phylogenetic analysis conducted by Zaher et al. (2020) is reproduced below.^[23]

The results of an earlier analysis by Pol & Rauhut (2012) are reproduced below.^[19]

See also

• Timeline of ceratosaur research
• 2004 in paleontology

References