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| Lanceirosphenodon ferigoloi
Vivar, Martinelli, Hsiou & Soares, 2020
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Abstract
We describe a new eusphenodontian, Lanceirosphenodon ferigoloi gen. et sp. nov., from the Upper Triassic (Norian) Riograndia Assemblage Zone (AZ) of the Candelária Sequence (Santa Maria Supersequence) of Rio Grande do Sul, Brazil. The new taxon consists of an almost complete left dentary with dentition, which exhibits a mosaic of features considered ‘typical’ of non-eusphenodontian rhynchocephalians, along with others reported for eusphenodontian taxa. It has the typical rhynchocephalian regionalized dentition with 19 teeth and also pleuroacrodont implantation; the additional dentition presents alternation of size and shape, with the last additional teeth resembling a spear in labial view. A well-developed chin is also present. Our phylogenetic analysis places Lanceirosphenodon as one of the most basal eusphenodontians and reinforces the hypothesis that Rhynchocephalia underwent an early diversification, probably in the Early Triassic, followed by an explosion in morphological disparity. Based on the ontogenetic sequence of Sphenodon, Lanceirosphenodon fitted between stages T2 and T3, representing a probable early juvenile individual. In spite of its ontogenetic stage, the set of characters present in Lanceirosphenodon, including two autapomorphies, supports its recognition as a new taxon. This new taxon increases our knowledge of the faunal diversity in the Triassic of Gondwana and more locally for the Riograndia Assemblage Zone of southern Brazil.
Keywords: Rhynchocephalia, Eusphenodontia, Riograndia Assemblage Zone, South America, Triassic
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| Dentary of Lanceirosphenodon ferigoloi gen. et sp. nov., CAPPA/UFSM 0226. |
Systematic palaeontology
Lepidosauria Haeckel, 1866
Rhynchocephalia Günther, 1867 (sensu Gauthier, Estes, & de Queiroz 1988)
Sphenodontia Williston, 1925 (sensu Benton 1985)
Eusphenodontia Herrera-Flores, Stubbs, Elsler, & Benton 2018
Lanceirosphenodon gen. nov.
Type and only species. Lanceirosphenodon ferigoloi
sp. nov.
Derivation of name. ‘Lanceiros’ in Portuguese means
‘spear’, in reference to the shape of the last additional
teeth that are reminiscent of a spearhead and in recognition of the ‘Lanceiros Negros’ (Black Lancers), a group
formed by slaves armed with long spears, who fought
for freedom during the Farroupilha Revolution in Rio
Grande do Sul State, Brazil (1835–1845), and whose
massacre brought about the end of the war. ‘Sphenodon’
refers to the extant genus Sphenodon.
Lanceirosphenodon ferigoloi sp. nov.
Derivation of name. In honour of Dr Jorge Ferigolo, a
renowned Brazilian palaeontologist based at the Museu
de Ciências Naturais of the Fundação Zoobotânica do
Rio Grande do Sul (MCN/FZBRS, Porto Alegre, Brazil),
who headed the Brazilian Pro-Guaíba Project, in which
several localities and new fossils from the Triassic of the
Rio Grande do Sul State were discovered, including the
first rhynchocephalian materials.
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Illustration: Jorge Blanco
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Conclusions:
In this contribution, we describe a new genus and species
of rhynchocephalian, Lanceirosphenodon ferigoloi, based on a well-preserved lower jaw with dentition.
This new taxon represents a basal eusphenodontian, with
a mosaic of plesiomorphic and apomorphic features.
Ontogenetically, the holotype specimen CAPPA/UFSM
0226 is considered to fall in stage T2–T3 of the ontogenetic series proposed by Robinson (1976) for Sphenodon,
which should correspond to an individual that was a few
months old. We infer an insectivorous diet for
Lanceirosphenodon based on its dental shape. The presence of this new sphenodontian increases the known
faunal diversity of the Riograndia AZ in the Brazilian
Triassic. Both this taxon and the Linha São Luiz site as a
whole are important in our understanding of the early
evolution of Rhynchocephalia in western Gondwana.
Based on our results, the early diversification of
Rhynchocephalia occurred around the Early Triassic, giving rise to the main lineages of the group.
Paulo R. Romo de Vivar, Agustín G. Martinelli, Annie Schmaltz Hsiou and Marina Bento Soares. 2020. A New Rhynchocephalian from the Late Triassic of Southern Brazil Enhances Eusphenodontian Diversity. Journal of Systematic Palaeontology. DOI: 10.1080/14772019.2020.1732488
Un nuevo lepidosaurio que vivio hace 227 millones de años en el sur de Brasil macnconicet.gob.ar/un-nuevo-lepidosaurio-que-vivio-hace-227-millones-de-anos-en-el-sur-de-brasil
