Spicomellus (meaning "collar of spikes") is an extinct genus of herbivorousankylosauriandinosaur that lived in the supercontinent Gondwana during the Middle Jurassic Period. The type and only known species is Spicomellus afer, named and described in 2021.[1][2] Its remains were found in the third subunit of the El Mers Group (Bathonian-Callovian), near Boulahfa, south of Boulemane, Fès-Meknès, Morocco.[2] The genus name means "spiked collar", from the Latin 'spica' meaning spike, and 'mellum' meaning spiked dog collar and the specific name 'afer' means "the African".[1]
During the Jurassic, eurypodan dinosaurs, in particular stegosaurs, were diverse and abundant in Laurasia (nowadays the northern continents), but their remains are extremely rare in Gondwanan deposits, nowadays the southern continents. Nevertheless, the existence of fragmentary remains and trackways in the deposits of Gondwana indicates the presence of eurypodan taxa there. Spicomellus is the second described eurypodan taxon from North Africa, after Adratiklit,[3][4] and the oldest known ankylosaur from anywhere in the world, with the possible exception of an unnamed thyreophoran from the Isle of Skye, Scotland that could be up to 2 million years older than Spicomellus, though it is still unknown if this older species was a stegosaur or an ankylosaur.[5] The holotype, NHMUK PV R37412, is housed at the Natural History Museum in London.[1]
It is unknown when the holotype specimen, NHMUK PV R37412, was discovered, but what is known is that it was acquired by the Natural History Museum from a commercial fossil dealer, Moussa Direct, based in Cambridge, U.K. in 2019.[1] Maidment initially believed that the fossil was a forgery, but after CT scanning the fossil, she drew the conclusion that it was a genuine fossil, and Spicomellus afer was described by Maidment et al., on the 23rd of September, 2021 in an article published online in paleontological journal Nature Ecology & Evolution.[1] The holotype of Spicomellus afer consists of a single rib with four co-ossified spines. This is a trait unique to Spicomellus and not known from any other vertebrate.[2] The holotype specimen was histologically sectioned to confirm that it was an ankylosaurian. The information about the locality of the fossil was provided by Direct and confirmed through discussion with the Moroccan fossil dealer who sold it to him. The locality was visited by S.C.R.M. and D.O. in 2019 and 2020, respectively, to study the sedimentology and stratigraphy of the area. They found that the formation consisted of shallow marine and continental mixed clastic, evaporitic and carbonate sediments.[4]
Description
Despite being a basal ankylosaurian, the preserved dermal spikes of the holotype were fused to the bone, which is a trait unique to Spicomellus and not known from any other vertebrate.[2] Because the dermal spikes were fused to the bone instead of being attached to muscle tissue in all other ankylosaurs, this trait would probably have made it harder for the animal to move.[2]
Though its exact size is unknown, it was likely comparable in size to other Middle Jurassic ankylosaurs like Sarcolestes and Tianchiasaurus.[1] This puts our best size estimates for Spicomellus at no longer than 3 metres (9.8 ft) when fully grown.
Classification
At first, Susannah Maidment was unsure whether Spicomellus was a stegosaur or an ankylosaur, but Maidment et al. (2021) confirmed that Spicomellus is a basal ankylosaurian. It was probably closely related to the only other known ankylosaurs that were alive at the same time, Sarcolestes and Tianchisaurus.[1] These species come from the U.K. and China, respectively.
Paleoecology
Spicomellus is only known from the El Mers Group's El Mers III Formation. It coexisted with the sauropod"Cetiosaurus" mogrebiensis (which may or may not be synonymous with the sauropod Atlasaurus from the contemporaneous terrestrial Guettioua Formation[6]) and the stegosaurAdratiklit,[4] browsing on low-growing plants and roots and tubers. Predators of the ecosystem consist of indeterminate theropods (possible megalosaurids).[7]
The discovery of Spicomellus also shows that the two major thyreophoran groups (Ankylosauria and Stegosauria) co-existed for over 20 million years, and implies that the extinction of the stegosaurs may have happened for other, still unknown reasons.[1]
References
^ abcdefghMaidment, Susannah C. R.; Strachan, Sarah J.; Ouarhache, Driss; Scheyer, Torsten M.; Brown, Emily E.; Fernandez, Vincent; Johanson, Zerina; Raven, Thomas J.; Barrett, Paul M. (2021-09-23). "Bizarre dermal armour suggests the first African ankylosaur". Nature Ecology & Evolution. 5 (12): 1576–1581. doi:10.1038/s41559-021-01553-6. ISSN 2397-334X. PMID 34556830. S2CID 237616095.
^ abcdeDavis, Josh (September 23, 2021). "New species of dinosaur had armour unlike anything seen before". Natural History Museum. Retrieved September 23, 2021.{{cite web}}: CS1 maint: url-status (link)
^"Reimagining dinosaurs". nationalgeographic.com. 15 September 2020.
^ abcMaidment, Susannah C. R.; Raven, Thomas J.; Ouarhache, Driss; Barrett, Paul M. (2019-08-16). "North Africa's first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity". Gondwana Research. 77: 82–97. doi:10.1016/j.gr.2019.07.007. ISSN 1342-937X.
^Clark, N.D.L. (2001). A thyreophoran dinosaur from the early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland. Scottish Journal of Geology, 37: 19—26.
^M. Monbaron, D. A. Russell, and P. Taquet. (1999). Atlasaurus imelakei n.g., n.sp., a brachiosaurid-like sauropod from the Middle Jurassic of Morocco. Comptes Rendus de l'Académie des Sciences à Paris, Sciences de la Terre et des Planètes 329:519-526.
^J. Jenny, A. Le Marrec, and M. Monbaron. (1981). Les empreintes de pas de dinosauriens dans le Jurassique moyen du Haut Atlas central (Maroc): nouveaux gisements et precisions stratigraphiques. Geobos. 14(3):427-431
spicomellus, meaning, collar, spikes, extinct, genus, herbivorous, ankylosaurian, dinosaur, that, lived, supercontinent, gondwana, during, middle, jurassic, period, type, only, known, species, afer, named, described, 2021, remains, were, found, third, subunit,. Spicomellus meaning collar of spikes is an extinct genus of herbivorous ankylosaurian dinosaur that lived in the supercontinent Gondwana during the Middle Jurassic Period The type and only known species is Spicomellus afer named and described in 2021 1 2 Its remains were found in the third subunit of the El Mers Group Bathonian Callovian near Boulahfa south of Boulemane Fes Meknes Morocco 2 The genus name means spiked collar from the Latin spica meaning spike and mellum meaning spiked dog collar and the specific name afer means the African 1 SpicomellusTemporal range Middle Jurassic 168 164 Ma PreꞒ Ꞓ O S D C P T J K Pg N Scientific classificationKingdom AnimaliaPhylum ChordataClade DinosauriaOrder OrnithischiaClade ThyreophoraSuborder AnkylosauriaGenus SpicomellusMaidment et al 2021Species S aferBinomial name Spicomellus aferMaidment et al 2021During the Jurassic eurypodan dinosaurs in particular stegosaurs were diverse and abundant in Laurasia nowadays the northern continents but their remains are extremely rare in Gondwanan deposits nowadays the southern continents Nevertheless the existence of fragmentary remains and trackways in the deposits of Gondwana indicates the presence of eurypodan taxa there Spicomellus is the second described eurypodan taxon from North Africa after Adratiklit 3 4 and the oldest known ankylosaur from anywhere in the world with the possible exception of an unnamed thyreophoran from the Isle of Skye Scotland that could be up to 2 million years older than Spicomellus though it is still unknown if this older species was a stegosaur or an ankylosaur 5 The holotype NHMUK PV R37412 is housed at the Natural History Museum in London 1 Contents 1 Discovery and naming 2 Description 3 Classification 4 Paleoecology 5 ReferencesDiscovery and naming EditIt is unknown when the holotype specimen NHMUK PV R37412 was discovered but what is known is that it was acquired by the Natural History Museum from a commercial fossil dealer Moussa Direct based in Cambridge U K in 2019 1 Maidment initially believed that the fossil was a forgery but after CT scanning the fossil she drew the conclusion that it was a genuine fossil and Spicomellus afer was described by Maidment et al on the 23rd of September 2021 in an article published online in paleontological journal Nature Ecology amp Evolution 1 The holotype of Spicomellus afer consists of a single rib with four co ossified spines This is a trait unique to Spicomellus and not known from any other vertebrate 2 The holotype specimen was histologically sectioned to confirm that it was an ankylosaurian The information about the locality of the fossil was provided by Direct and confirmed through discussion with the Moroccan fossil dealer who sold it to him The locality was visited by S C R M and D O in 2019 and 2020 respectively to study the sedimentology and stratigraphy of the area They found that the formation consisted of shallow marine and continental mixed clastic evaporitic and carbonate sediments 4 Description EditDespite being a basal ankylosaurian the preserved dermal spikes of the holotype were fused to the bone which is a trait unique to Spicomellus and not known from any other vertebrate 2 Because the dermal spikes were fused to the bone instead of being attached to muscle tissue in all other ankylosaurs this trait would probably have made it harder for the animal to move 2 Though its exact size is unknown it was likely comparable in size to other Middle Jurassic ankylosaurs like Sarcolestes and Tianchiasaurus 1 This puts our best size estimates for Spicomellus at no longer than 3 metres 9 8 ft when fully grown Classification EditAt first Susannah Maidment was unsure whether Spicomellus was a stegosaur or an ankylosaur but Maidment et al 2021 confirmed that Spicomellus is a basal ankylosaurian It was probably closely related to the only other known ankylosaurs that were alive at the same time Sarcolestes and Tianchisaurus 1 These species come from the U K and China respectively Paleoecology EditSpicomellus is only known from the El Mers Group s El Mers III Formation It coexisted with the sauropod Cetiosaurus mogrebiensis which may or may not be synonymous with the sauropod Atlasaurus from the contemporaneous terrestrial Guettioua Formation 6 and the stegosaur Adratiklit 4 browsing on low growing plants and roots and tubers Predators of the ecosystem consist of indeterminate theropods possible megalosaurids 7 The discovery of Spicomellus also shows that the two major thyreophoran groups Ankylosauria and Stegosauria co existed for over 20 million years and implies that the extinction of the stegosaurs may have happened for other still unknown reasons 1 References Edit a b c d e f g h Maidment Susannah C R Strachan Sarah J Ouarhache Driss Scheyer Torsten M Brown Emily E Fernandez Vincent Johanson Zerina Raven Thomas J Barrett Paul M 2021 09 23 Bizarre dermal armour suggests the first African ankylosaur Nature Ecology amp Evolution 5 12 1576 1581 doi 10 1038 s41559 021 01553 6 ISSN 2397 334X PMID 34556830 S2CID 237616095 a b c d e Davis Josh September 23 2021 New species of dinosaur had armour unlike anything seen before Natural History Museum Retrieved September 23 2021 a href Template Cite web html title Template Cite web cite web a CS1 maint url status link Reimagining dinosaurs nationalgeographic com 15 September 2020 a b c Maidment Susannah C R Raven Thomas J Ouarhache Driss Barrett Paul M 2019 08 16 North Africa s first stegosaur Implications for Gondwanan thyreophoran dinosaur diversity Gondwana Research 77 82 97 doi 10 1016 j gr 2019 07 007 ISSN 1342 937X Clark N D L 2001 A thyreophoran dinosaur from the early Bajocian Middle Jurassic of the Isle of Skye Scotland Scottish Journal of Geology 37 19 26 M Monbaron D A Russell and P Taquet 1999 Atlasaurus imelakei n g n sp a brachiosaurid like sauropod from the Middle Jurassic of Morocco Comptes Rendus de l Academie des Sciences a Paris Sciences de la Terre et des Planetes 329 519 526 J Jenny A Le Marrec and M Monbaron 1981 Les empreintes de pas de dinosauriens dans le Jurassique moyen du Haut Atlas central Maroc nouveaux gisements et precisions stratigraphiques Geobos 14 3 427 431 Portals Dinosaurs Paleontology Morocco Biology Retrieved from https en wikipedia org w index php title Spicomellus amp oldid 1098091206, wikipedia, wiki, book, books, library,
