Paranthodon

This article has been published in the peer-reviewed journal WikiJournal of Science (2020). Click to view the published version.
Source: Wikipedia, the free encyclopedia.

Paranthodon
Temporal range:
Ma
↓
Possible Late Jurassic record
Skull of Paranthodon
Reconstruction of the skull; grey material is unknown.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: †Ornithischia
Clade: †Thyreophora
Clade: †Stegosauria
Family: †Stegosauridae
Genus: †Paranthodon
Nopcsa, 1929[2]
Species:
†P. africanus
Binomial name
†Paranthodon africanus
Broom, 1912[1]
Synonyms[4]

Paranthodon (

Franz Nopcsa, unaware of Broom's new name, similarly concluded that it represented a new taxon, and named it Paranthodon owenii. Since Nopcsa's species name was assigned after Broom's, and Broom did not assign a new genus, both names are now synonyms of the current binomial, Paranthodon africanus. The genus name combines the Ancient Greek
para (near) with the genus name Anthodon, to represent the initial referral of the remains.

In identifying the remains as those of Palaeoscincus, Broom initially classified Paranthodon as an

stegosaurid
, with which most modern studies agree. In 1981, the genus was reviewed with modern taxonomic techniques, and found to be a valid genus of stegosaurid. A 2018 review of Paranthodon could only identify one distinguishing feature, and while that study still referred it to Stegosauria based on similarity and multiple phylogenetic analyses, no diagnostic features of the group could be identified in Paranthodon.

History of discovery

Anthodon serrarius
, to which the skull of Paranthodon was originally assigned

In 1845, amateur geologists

vertebrae BMNH 47337a were all assigned to Anthodon.[10] In 1882, Othniel Charles Marsh assigned Anthodon to Stegosauridae based on BMNH 47338, and in 1890, Richard Lydekker found that although Anthodon was a pareiasaur, its teeth were similar to those of the Stegosauridae.[10] Lydekker in 1890 also corrected a mistake of Owen, who had incorrectly summarised all the material as coming from a single locality, whereas there was separate material from two clearly distinct localities.[7]

In 1909,

British Museum of Natural History. He concluded that Owen had mixed the partial distorted skull, teeth, and a mandible of a pareiasaur and a partial upper jaw of a dinosaur, BMNH 47338, which were from two different species.[1][3] Broom kept the name Anthodon for the pareiasaur, but identified the other fossil as a member of the genus Palaeoscincus, naming the new species Palaeoscincus africanus in 1912. He found that the anatomy of the teeth were quite different, even though they resembled each other, as well as those of Stegosaurus.[7][1] In 1929, Franz Nopcsa, unaware of Broom's previous publication, provided a second novel name as D. M. S. Watson believed that the jaw should be differentiated from Anthodon.[7][2] Nopcsa named the species Paranthodon Owenii, with the generic name derived from the Latin para, meaning "similar", "near", or "beside", and Anthodon, and specific name honouring Owen.[2][5][11] Following modern conventions, the specific name was later emended to owenii.[10] Both names were brought into the current nomenclature by Walter P. Coombs in his 1971 dissertation as the new combination Paranthodon africanus, as the name Paranthodon was the first new generic name for the fossils and africanus was the first new specific name.[7][12] This makes Paranthodon africanus the proper name for the taxon previously known as Palaeoscincus africanus and Paranthodon owenii.[7][10]

Material

Previously referred tooth (NHMUK R4992)

The holotype of Paranthodon, BMNH 47338, was found in a layer of the Kirkwood Formation that has been dated between the Berriasian and early Valanginian ages. It consists of the back of the snout, containing the maxilla with teeth, the posterior caudodorsal ramus of the premaxilla, part of the nasals, and some isolated teeth probably from the lower jaw. One additional specimen was assigned to it based on the dentition, BMNH (now NHMUK) R4992, including only isolated teeth sharing the same morphology as those from the holotype.[10] Some bones that were unidentified by Galton & Coombs (1981) were described as a fragment of a vertebra in 2018 by Raven & Maidment.[4] The teeth do not bear any autapomorphies of Paranthodon, and were referred to an indeterminate stegosaurid in 2008.[13] The teeth were identified in 2018 as also lacking any distinct stegosaurian features, and were thus designated as Thyreophora indeterminate.[4]

The Mugher Mudstone of Ethiopia was screened in the 1990s by the University of California Museum of Paleontology, and in it were discovered multiple dinosaur teeth, pertaining to many groups of taxa. The locality has been described as "the largest and most complete record of dinosaur fossils from a Late Jurassic African locality outside of Tendaguru". Two of the partial teeth discovered were referred to Paranthodon by Lee Hall and Mark Goodwin in 2011. The reasons for the referral to Paranthodon were not discussed.[14]

Description

Silhouette of Paranthodon is shown to be three times longer than the human silhouette is tall
Size comparison with a human

Paranthodon was a small relative of larger stegosaurids such as Stegosaurus.

nares are large. The teeth have a prominent primary ridge. The fossilised nasal and maxillary bones are relatively complete, and an incomplete premaxilla is also preserved. The partial snout resembles Stegosaurus in its large posterior premaxillary process and the extension of the palate. Stegosaurus was the only stegosaurid known from adequate cranial material to compare with Paranthodon during the 1981 review of the taxon, and even though their resemblance is great, tooth morphology is very distinguishing among the stegosaurians. For example, cranial material is known from Stegosaurus, Paranthodon, Kentrosaurus, and Tuojiangosaurus, and the tooth morphology differs in all of them.[10]

Maxilla and premaxilla in multiple views

The premaxilla of Paranthodon is incomplete, but the anterior process is sinuous and curves

tooth row is horizontal in lateral view, and in ventral view it is sinuous. Stegosaurus and Huayangosaurus possess a straight tooth row in ventral view, although Scelidosaurus and Jiangjunosaurus do not.[4] The maxilla of Paranthodon preserves the tooth row, and shows that there is little to no overhang. This differs from ankylosaurians, where there is a large overhang of the maxilla.[16] As with Stegosaurus and Silvisaurus, there is a diastema (gap in the tooth row) on the maxilla in front of the tooth row. The posterior maxilla is incomplete so no information is known about the jugal or lacrimal contact.[4] Paranthodon has an elongate, dorsally convex nasal, like in most other stegosaurs. There are thickened ridges along the sides of the nasals. The preserved portion of the nasal does not contact the premaxilla or maxilla.[4]

Known vertebra fragments, compared to a complete Stegosaurus dorsal vertebra (F)

Thirteen teeth are preserved in Paranthodon, but as they extend to the back of the maxilla there were possibly more in life. The teeth are symmetrical as in stegosaurs except Chungkingosaurus. Along the base of the

tooth crown there is a swelling (cingulum), which is seen in all other known stegosaurid teeth except Huayangosaurus.[4] The teeth have a middle ridge, with five fewer prominent ridges on either side. This is similar to the size ridges seen on Kentrosaurus.[16] Like all stegosaurians, the denticles on the teeth are rounded at the tips, in contrast to ankylosaurians. Also, like Huayangosaurus, but unlike Kentrosaurus and Stegosaurus, Paranthodon possesses a prominent buccal margination (a ridge beside the tooth row). Paranthodon teeth preserve wear, but wear is absent on most teeth, similar to Huayangosaurus, meaning it is likely that Paranthodon lacked occlusion between teeth.[17]

As only two fragments of a vertebra are known, few anatomical details can be observed. The right

prezygapophysis are preserved. The vertebra is possibly a middle dorsal, based on the angle of the transverse process and the orientation of the prezygapophysis. Similar to Stegosaurus and Chungkingosaurus mid-dorsals, the transverse process is angled about 60º dorsally. Unlike in all other stegosaurs except Stegosaurus, the prezygapophysis faces dorsally.[4]

Classification

Currently, Paranthodon is classified as a stegosaur related to Stegosaurus, Tuojiangosaurus, and Loricatosaurus. Initially, when Broom assigned the name Palaeoscincus africanus to the Paranthodon fossils, he classified them as an ankylosaurian. This classification was later changed by Nopcsa, who found that Paranthodon best resembled a stegosaurid (before the group was truly defined[18]). Coombs (1978) did not follow Nopcsa's classification, keeping Paranthodon as an ankylosaurian, like Broom, although he only classified it as Ankylosauria incertae sedis.[19] A subsequent review by Galton and Coombs in 1981 instead confirmed Nopcsa's interpretation, redescribing Paranthodon as a stegosaurid from the Lower Cretaceous.[10][16] Paranthodon was distinguished from other stegosaurs by a long, wide, posterior process of the premaxilla, teeth in the maxilla with a very large cingulum, and large ridges on the tooth crowns.[11] Not all of these features were considered valid in a 2008 review of Stegosauria, with the only autapomorphy found being the possession of a partial second bony palate on the maxilla.[13]

stegosaurians

Multiple phylogenetic analyses have placed Paranthodon in Stegosauria, and often in Stegosauridae. A 2010 analysis including nearly all species of stegosaurians found that Paranthodon was outside Stegosauridae, and in a polytomy with Tuojiangosaurus, Huayangosaurus, Chungkingosaurus, Jiangjunosaurus, and Gigantspinosaurus. When the latter two genera were removed, Paranthodon grouped with Tuojiangosaurus just outside Stegosauridae, and Huayangosaurus grouped with Chungkingosaurus in Huayangosauridae.[20] An elaboration upon this analysis was published in 2017 by Susannah Maidment and Thomas Raven, and it resolved relationships within Stegosauria much more. All taxa were remained included, and Paranthodon grouped with Tuojiangosaurus, Huayangosaurus and Chunkingosaurus as the most basal true stegosaurians. The position of Alcovasaurus was uncertain, and further work could change the result. Below is the analysis.[21]

Nasal bones
of Paranthodon in multiple views
Thyreophora

Lesothosaurus diagnosticus

Laquintasaura venezuelae

Scutellosaurus lawleri

Emausaurus ernsti

Scelidosaurus harrisonii

Alcovasaurus longispinus

Eurypoda
Ankylosauria

Sauropelta edwardsi

Gastonia burgei

Euoplocephalus tutus

Stegosauria

Huayangosaurus taibaii

Chungkingosaurus jiangbeiensis

Tuojiangosaurus multispinus

Paranthodon africanus

Jiangjunosaurus junggarensis

Gigantspinosaurus sichuanensis

Kentrosaurus aethiopicus

Dacentrurus armatus

Loricatosaurus priscus

Hesperosaurus mjosi

Miragaia longicollum

Stegosaurus stenops

Stegosaurus homheni

Other analyses have found Paranthodon closely related to Tuojiangosaurus, Loricatosaurus, and Kentrosaurus within

synapomorphies of Stegosauria. The material is likely of stegosaurian nature, and phylogenies by many authors have found it to be within the group.[20]

Paleoecology

Map showing the Eastern Cape off the coast of South Africa, with the Kirkwood Formation near the southern coast
Map showing the Eastern Cape off the coast of South Africa, with the Kirkwood Formation near the southern coast
Kirkwood Formation
class=notpageimage|
The Kirkwood Formation, the location of the fossil discovery

The Kirkwood Formation is in South Africa, and many fossils of different

diplodocid.[25]

If the referral of teeth from Ethiopia to Paranthodon is correct, then the taxon's geographic range is extended significantly. The Mugher locality is approximately 151 million years old, about 14 million older than has previously been suggested for Paranthodon, as well as across both southern and eastern Africa. The fauna in the Mugher locality differ from elsewhere of the same time and place in Africa. While the Tendaguru has abundant stegosaurs, sauropods,

theropods, the Mugher Mudstone preserves the stegosaur Paranthodon, a hypsilophodontid ornithopod, a probable sauropod, and theropods related to Allosauridae and Dromaeosauridae.[14]

References

This article was submitted to WikiJournal of Science for external academic peer review in 2018 (reviewer reports). The updated content was reintegrated into the Wikipedia page under a CC-BY-SA-3.0 license (2019). The version of record as reviewed is: Iain Reid; et al. (2020). "Paranthodon" (PDF). WikiJournal of Science. 3 (1): 1.

Wikidata Q83852037.{{cite journal}}: CS1 maint: unflagged free DOI (link
)

  1. ^
    doi:10.1080/00359191009519357
    .
  2. ^ a b c d Nopsca, F. (1929). "Dinosaurierreste aus Siebenburgen V. Geologica Hungarica. Series Palaeontologica". Fasciculus. 4 (1): 13.
  3. ^ a b c Owen, R. (1876). "Descriptive and illustrated catalogue of the fossil Reptilia of South Africa in the collection of the British Museum". Order of the Trustees: 14–15.
  4. ^
    PMID 29576986
    .
  5. ^
    ISBN 978-0-375-92419-4
    .
  6. ^ a b Atherstone, W.G. (1857). "Geology of Uitenhage". The Eastern Province Monthly Magazine. 1 (10): 518–532.
  7. ^
    ISSN 1562-5273. Archived
    from the original on 31 January 2019. Retrieved 31 January 2019.
  8. doi:10.1016/j.jafrearsci.2005.07.014
    .
  9. ^ Atherstone, W.G. (1871). "From Graham's Town to the Gouph". Selected articles from the Cape Monthly Magazine (New Series 1870–76). Cape Town: Van Riebeeck Society.
  10. ^
    doi:10.1016/S0016-6995(81)80177-5
    .
  11. ^
    ISBN 978-0-7864-7222-2
    .
  12. ^ Olshevsky, G. (1978). "The Archosaurian Taxa (excluding the Crocodylia)". Mesozoic Meanderings (1): 1–50.
  13. ^
    S2CID 85673680
    .
  14. ^
    doi:10.13140/RG.2.1.3740.7763. Archived
    (PDF) from the original on 14 December 2017. Retrieved 13 December 2017.
  15. ^ Holtz, T.R. Jr. (2014). "Supplementary Information to Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages". University of Maryland. Archived from the original on 2 November 2014. Retrieved 5 September 2014.
  16. ^
    ISSN 0077-7749
    .
  17. ISBN 978-0-253-33964-5
    .
  18. ^ Sereno, P.C. (2005). "Stegosauridae". TaxonSearch: Database for Suprageneric Taxa & Phylogenetic Definitions. Archived from the original on 1 July 2015. Retrieved 2 October 2014.
  19. ^ Coombs, W.P. Jr. (1978). "The Families of the Ornithischian Dinosaur Order Ankylosauria" (PDF). Palaeontology. 21 (1): 143–170. Archived from the original (PDF) on 8 July 2015. Retrieved 3 January 2017.
  20. ^
    S2CID 84415016
    .
  21. S2CID 55613546. Archived
    (PDF) from the original on 19 August 2018. Retrieved 6 August 2018.
  22. ISBN 978-0-253-00849-7
    .
  23. ^
    S2CID 131280290
    .
  24. ISSN 0213-6937
    .
  25. ^
    hdl:10044/1/27470
    .
  26. S2CID 129160518
    .
  27. ISBN 978-0-12-226810-6
    .

See also

Retrieved from "https://en.wikipedia.org/w/index.php?title=Paranthodon&oldid=1209201018"