Жұқа қабатты динозавр - Rugops primus

Genus of dinosaur

Rugops (meaning ‘wrinkle face’) is a monospecific genus of basal abelisaurid theropod dinosaur from Niger that lived during the Late Cretaceous period (Cenomanian stage, ~95 Ma) in what is now the Echkar Formation. The type and only species, Rugops primus, is known only from a partial skull. It was named and described in 2004 by Paul Sereno, Jeffery Wilson and Jack Conrad. Rugops has an estimated length of 4.4–5.3 metres (14.4–17.4 ft) and weight of 410 kilograms (900 lbs). The top of its skull bears several pits which correlates with overlaying scale and the front of the snout would have had an armour like dermis.

A skull pertaining to an abelisaurid was recovered during an expedition in 2000 led by Paul Sereno near In Abangharit, Niger Republic. The specimen came from the Echkar Formation of the Tegama Group which dates to the Cenomanian stage of the Late Cretaceous period, 96 Ma. The formation has also yielded specimens pertaining to the carcharodontosaurid Carcharodontosaurus iguidensis, the spinosaurid Spinosaurus, Laganosuchus and Kaprosuchus. The specimen was described in 2004 by Paul Sereno, Jeffery Wilson and Jack Conrad. The holotype specimen, MNN IGU1, consists of a partial skull which lacks portions of the palate and skull roof. However, the maxilla cannot be referred to Rugops as the diagnostic features of the genus are located on different parts of the skull.

In 2010, Gregory S. Paul gave Rugops an estimated length of 6 metres (19.7 ft) and weight of 750 kilograms (1,650 lbs). 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.

The skull length of Rugops was about 31.5 centimetres (12.4 inches). Sereno et al. (2004) suggested that the depressions on the dorsal surface of each nasal anchored either sensory structures or soft tissues for display. 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. 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. 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. Delcourt (2018), and Rolando et al. (2020). 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), Rauhut & Carrano (2016), and Iori et al. (2021). Other alternative positions include Rugops being more derived than Kryptops, Chenanisaurus and/or Spectrovenator as recovered by Sereno & Brusatte (2008), Zaher et al. (2020), Gianechini et al. (2021) and Agnolín et al. (2022), and within a polytomy with other abelisaurids such as Xenotarsosaurus, Tarascosaurus, Ilokelesia and Genusaurus which has been recovered by Tortosa et al. (2014), Baiano et al. (2020) and Salem et al. (2022). A phylogenetic analysis conducted by Zaher et al. (2020) is reproduced below. The results of an earlier analysis by Pol & Rauhut (2012) are reproduced below.