Pararhabdodon

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Pararhabdodon
Temporal range:
Ma
↓
Maxillae
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: †Ornithischia
Clade: †Ornithopoda
Family: †Hadrosauridae
Subfamily: †Lambeosaurinae
Tribe: †Tsintaosaurini
Genus: †Pararhabdodon
Casanovas-Cladellas, Santafé-Llopis & Isidro-Llorens, 1993
Type species
†Pararhabdodon isonensis
Casanovas-Cladellas, Santafé-Llopis & Isidro-Llorens, 1993
Synonyms

Pararhabdodon (meaning "near fluted tooth" in reference to

Cretaceous-Paleogene extinction event.[1]

Initially, the material was thought to belong to a

hadrosauroid. In 2009 evidence was put forward that it was indeed a lambeosaurine, and more specifically a close relative of Tsintaosaurus, a genus from China. This position has been repeatedly found since, and the group containing them was later named Tsintaosaurini. A different position, related to other European lambeosaurs in the group Arenysaurini
, was proposed in 2020.

History and assigned material

Sant Romà d’Abella material

Stratigraphic map of hadrosaur localities in the Pyrenees, including SRA[b]

Excavation of specimens that would later be used to erect Pararhabdodon began in Spring 1985, at the Sant Romà d’Abella (SRA) locality (in the

iguanodont, hence the name; isonense was in reference to Isona.[6]

Additional material from the type locality was collected in 1994 - including two

lambeosaurine hadrosaur, in a paper again by Casanovas-Cladellas et al.. This made it the first member of the subfamily from the continent, and the second valid hadrosaur, preceded by Telmatosaurus and the dubious Orthomerus.[4][9]

In total, known material from the type locality includes: a left and a right maxilla; five cervical, five

caudal vertebra; a sacrum; fragmentary rib bones; one end of the right ischium; a fragment of the left scapula, an ulna and a humerus.[3][4][10] All of this material was excavated from a 4 metres (13 ft) by 2.5 metres (8.2 ft) surface, and it is thought to have belonged to a single individual.[4] The holotype is a nearly complete caudally located cervical vertebra (a cervical vertebra located near the base of the neck), specimen number IPS SRA-1.[3][5] Another cervical, a humerus, and an ulna were designated the paratype specimens.[4] In 2020, Jesús F. Serrano and colleagues described new hindlimb material from the site, found in 2018. These are thought to belong to the holotype individual. This includes a femur, a partial tibia, a complete fibula, and a haemal arch.[11]

Referred material from other localities

Map of lambeosaur localities in the Pyrenees; MCD 4919 is labelled as belonging to Pararhabdodon

In their 1997 paper, Laurent and colleagues referred remains from the Le Bexen site of the uppermost

Canardia garonnensis.[10]

A maxilla, specimen MCD 4919, was referred to P. isonensis in 2013. It possessed traits of the tsintaosaurin

strata, making it older. The referral to Pararhabdodon thus extended the range of the genus further within the upper Maastrichtian.[10][13] A 2019 paper questioned the referral of MCD 4919 to P. isonensis. The specimen was found to have a differing ectopterygoid shelf compared to the maxilla of the holotype, which would conflict with belonging to the same species. As the specimen was still recognized as having tsintaosaurin characteristics, the authors still considered it to likely belong to a close relative of P. isonensis.[13]

A selection of dentary material from the Basturs Poble bonebed

The same 2013 study also evaluated

synonymous, representatives of a single species. The same re-evaluation could not rule out that this single species or either of the separated species were synonyms of Pararhabdodon isonensis, as no taxonomically informative areas of the skeleton are known from both Pararhabdodon and the other two taxa. The authors refrained from considering any of them representatives of one species pending data from more material.[10] The Pararhabdodon himdlimb described in 2020 allowed for synonymy with Arenysaurus to be ruled out, as the femurs of the two taxa were anatomically distinct.[11]

A hadrosaur mega-bonebed, later termed the Basturs Poble bonebed, was discovered in outcrops of the Conques Formation[c] during the late 1990s. The taxonomic status of this bonebed has fluctuated over time.[14] It has been debated whether the material represents a singular species or a combination of two distinct ones; but today a single, variable species is considered most likely.[14][15] It was suggested the material likely belong to Koutalisaurus, based on geographic proximity, but this reassignment was abandoned when that genus was recognized as indeterminate.[10][16] Since then, it has instead been tentatively assigned to the genus Pararhabdodon.[14] However, due to the lack of any suitable material for comparison and the lack of tsintaosaurin characteristics in the bonebed material, it has been more recently suggested that it should instead be considered indeterminate lambeosaur material.[13] The 2020 hindlimb description allowed for distinction between Pararhabdodon and the Basturs Poble material to be solidified, with the bonebed material showing inconsistent femoral anatomy with the genus.[11]

Relationship with "Koutalisaurus"

Holotype dentary and only specimen of "Koutalisaurus kohlerorum", considered at different times a distinct taxon, specimen of P. isonensis, or indeterminate lambeosaurine specimen

Near the village

synonymization of their taxon with P. isonensis[3]

Tsintaosaurus spinorhinus

Evidence for this synonymy would later come in a 2009 study, from Prieto-Márquez alongside Jonathan R. Wagner. Material from Pararhabdodon, the holotype of Koutalisaurus, and material of the Chinese species

Tsintaosaurus spinorhinus were examined and compared, and the edentulous slope previously thought unique to Koutalisaurus was found to be nearly identical in T. spinorhinus. No material had, as yet, been discovered from the SRA locality permitting comparison with Pararhabdodon. However, traits uniting P. isonensis with T. spinorhinus were found. As both taxa from the Talarn Formation[c] uniquely shared traits with the Asian genus, the authors decided to treat the two as one species, as maintaining them as provisionally separate would in their eyes be misleading to non-specialists, who would likely not distinguish that the two taxa were being kept separate to be conservative and not due to strong evidence for two hadrosaurs in the area.[17]

Prieto-Márquez returned again to the dentary in 2013, in a study alongside colleagues providing a review and investigation of hadrosaurs from all over Europe. Further preparation of the specimen in the time since his last study regarding it revealed the uniqueness of the dentary had been exaggerated significantly by reconstruction of the specimen when it was first prepared in the 1990s. The Tsintaosaurus specimens showing the similar condition were found to have been distorted from a similar process. Correcting for the inaccuracies, the Los Llaus dentary is indistinguishable from that of multiple lambeosaurines, and shares no particular connection to Tsintaosaurus. With this, their reasoning for assignment of the specimen to Pararhabdodon was voided, and the specimen is now considered a completely indeterminate lambeosaurine dentary.[10]

Description

Estimated size of the holotype and a hypothetical adult

Pararhabdodon would have been a

quadrupedal herbivore. The holotype specimen is estimated to have been around 6 metres (20 ft) long.[3] Histological analysis indicates the individual was not fully grown, and so the species likely reached similar sizes to North American and Asian relatives such as Corythosaurus and Tsintaosaurus (around 9 metres (30 ft) long[18]). This is despite Pararhabdodon living on an island, something generally associated with insular dwarfism, a phenomenon exhibited in other European hadrosaurs; Adynomosaurus was cited as a similar example, being around the same size.[11]

Classification

Modern life reconstruction of a Rhabdodon, which Pararhabdodon was originally thought to be closely related to

Pararhabdodon has been classified in a number of different positions within

hadrosaur.[8]

Life restoration of Pararhabdodon

Casanovas-Cladellas

neural spines, and deltopectoral crest of the humerus being distally projected.[4]

The proposal that P. isonensis was the first known European lambeosaurine was soon challenged, however, in 2001 by Jason Head, in a study re-evaluating the status of another species,

phylogenetic analysis for the first time. This found it to be a non-hadrosaurid hadrosauroid, a similar position as had been argued by Head. The cladogram of Prieto-Márquez et al. (2006) is seen below on the left:[3]

Iguanodon bernissartensis

Iguanodon atherfieldensis

Probactrosaurus gobiensis

Ouranosaurus nigeriensis

Protohadros byrdi

Bactrosaurus johnsoni

Gilmoreosaurus mongoliensis

Telmatosaurus transsylvanicus

Tanius sinensis

Pararhabdodon isonensis

Hadrosauridae

Equijubus normani

Probactrosaurus gobiensis

Protohadros byrdi

Eolambia caroljonesa

Tanius sinensis

Bactrosaurus johnsoni

Telmatosaurus transsylvanicus

Tethyshadros insularis

Lophorhothon atopus

Hadrosauridae

Hadrosaurus foulkii

Edmontosaurus annectens

Brachylophosaurus canadensis

Lambeosaurinae

Aralosaurini

Jaxartosaurus aralensis

Tsintaosaurini

Tsintaosaurus spinorhinus

Pararhabdodon isonensis

Skull of Tsintaosaurus

Prieto-Márquez would return to the issue in 2009 along with Jonathan R. Wagner. They once again turned to the articulation between the maxilla and the jugal, finding this to link Pararhabdodon to the Asian lambeosaurine,

tribe Tsintaosaurini; a diagnosis for the tribe was provided. Their cladogram is reproduced above, on the right.[10]

Maxilla specimen MCD 4919 from the Serrat del Rostiar 1 locality
Fossils of Arenysaurus, proposed by Longrich and colleagues to be a close relative of Pararhabdodon

In a 2020 study describing and naming

monophyletic clade, which was therein named Arenysaurini. A unique combination of primitive and derived anatomical features, as well as some unique to the group, supported them forming a clade. Tsintaosaurus was not found to be close to Pararhabdodon, instead taking a more basal position.[21]

Hadrosauridae

See also

References

Notes

  1. ^ a b c d The geologic unit has been variously divided as the Tremp Formation, composed of several units, or the Tremp Group, composed of several formations. This article will use the Tremp Group terminology throughout for consistency.
  2. ^ Lower Red Unit equivalent to Talarn Formation and Gray Unit equivalent to La Posa Formation under Tremp Group nomenclature
  3. ^ a b c d e Equivalent to part of the "Lower Red Unit" or "Lower Red Garumnian" unit under the Tremp Formation nomenclature.
  4. ^ Equivalent to the "Grey Unit" or "Grey Garumnian" unit under the Tremp Formation nomenclature.

Citations

  1. S2CID 225110719
    . Retrieved 3 May 2021.
  2. S2CID 208195457
    .
  3. ^ a b c d e f g h i j k l Prieto-Marquez, A., Gaete, R., Rivas, G., Galobart, Á., and Boada, M. (2006). Hadrosauroid dinosaurs from the Late Cretaceous of Spain: Pararhabdodon isonensis revisited and Koutalisaurus kohlerorum, gen. et sp. nov. Journal of Vertebrate Paleontology 26(4): 929-943.
  4. ^ a b c d e f g h Casanovas, M.L, Pereda-Suberbiola, X., Santafé, J.V., and Weishampel, D.B. (1999). First lambeosaurine hadrosaurid from Europe: palaeobiogeographical implications. Geological Magazine 136(2):205-211.
  5. ^ a b c Casanovas, M.L, Santafé, J.S., Sanz, J.L., and Buscalioni, A.D. (1987). Arcosaurios (Crocodilia, Dinosauria) del Cretácico superior de la Conca de Tremp (Lleida, España) [Archosaurs (Crocodilia, Dinosauria) from the Upper Cretaceous of the Tremp Basin (Lleida, Spain)]. Estudios Geológicos. Volumen extraordinario Galve-Tremp:95-110. [Spanish]
  6. ^ a b Casanovas-Cladellas, M.L., Santafé-Llopis, J.V., and Isidro-Llorens, A. (1993). Pararhabdodon isonensis n. gen. n. sp. (Dinosauria). Estudio mofológico, radio-tomográfico y consideraciones biomecanicas [Pararhabdodon isonense n. gen. n. sp. (Dinosauria). Morphology, radio-tomographic study, and biomechanic considerations]. Paleontologia i Evolució 26-27:121-131. [Spanish]
  7. ^ a b Laurent, Y., LeLoeuff, J., & Buffetaut, E. (1997). Les Hadrosauridae (Dinosauria, Ornithopoda) du Maastrichtien supérieur des Corbières orientales (Aude, France) [The Hadrosauridae (Dinosauria, Ornithopoda) from the Upper Maastrichtian of the eastern Corbières (Aude, France)]. Revue de Paléobiologie 16:411-423. [French]
  8. ^ a b c Casanovas-Cladellas, M. L.; Santafé-Llopis, J. V.; Pereda-Suberbiola, X. (1997). "New remains of Pararhabdodon isonensis (Dinosauria, Hadrosauridae) and a synthesis of the assemblage of material discovered in the Upper Cretaceous of Catalonia". Second Workshop of Vertebrate Paleontology, Abstracts (Unpaginated). Espéraza-Quillan.
  9. ^ Casanovas-Cladellas, M. L., Santafé-Llopis, J. V., & Pereda-Suberbiola, X. (1997). Nouveaux restes de Pararhabdodon (Dinosauria, Hadrosauridae) et synthèse de l’ensemble du materiel découvert dans le Cretacé supérieur de Catalogne. In Second European Workshop of Vertebrate Paleontology, Abstracts (unpaginated).
  10. ^
    PMID 23922815
    .
  11. ^
    S2CID 225110719
    .
  12. ^ Laurent, Y. (2002). Les faunes de vertébrés continentaux du Maastrichtien supérieur d'Europe: systématique et biodiversité (Doctoral dissertation, Toulouse 3).
  13. ^
    S2CID 134582286
    .
  14. ^
    PMID 30379888
    .
  15. doi:10.1016/j.cretres.2015.04.001
    .
  16. ^ Prieto-Márquez A, Gaete R, Galobart A, Riera V. New data on European Hadrosauridae (Dinosauria: Ornithopoda) from the latest Cretaceous of Spain. J Vertebr Paleontol. 2007;27(3): 131A.
  17. ^
    S2CID 85081036
    .
  18. ISBN 978-0-7566-9910-9
    .
  19. doi:10.1111/j.1096-3642.2009.00617.x
    .
  20. S2CID 85705882
    .
  21. S2CID 228807024
    .
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