A new ‘archaeohyracid’ (Notoungulata, Typotheria) from the Eocene of north-western Argentina: anatomy, phylogenetic relationships and evolutionary implications

FERRO, AGOSTINA; GARCÍA-LÓPEZ, DANIEL A.; SAADE, LUIS S.; ALONSO-MURUAGA, PABLO J.; SCANFERLA, AGUSTÍN

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Año: 2023 vol. 21

1477-2019

Here we describe a new notoungulate taxon, Pascualhyrax irqisp. nov., from Eocene levels of north-western Argentina. The materials studiedinclude cranial and dental remains and were exhumed in sediments of theQuebrada de los Colorados Formation, corresponding to the late middle Eocene(Bartonian). General traits of the referred specimens (e.g. hypsodontpostcanines, nasal bulge) point to a close relationship with differenttypotherian taxa traditionally included among the paraphyletic ‘Archaeohyracidae’.In turn, a combination of characters indicates that the new material representsa new taxon (e.g. smaller size, deep ectoflexus in upper molars in all wearstages, maxillary process extending posterior to the caudal end of the nasals).A phylogenetic analysis was performed, based in a previously published matrixand the addition of new characters, resulting in a close relationship ofPascualhyrax irqi sp. nov. with different ‘Archaeohyracidae’ ofOligocene radiation. This fact shows the early expression of some charactersuntil now only known for later forms, and developed in the context of arecently acknowledged diversity of hypsodont typotherians in north-westernArgentina. Regarding other evolutionary issues, the strong similitude of thejuvenile specimens referred to Pascualhyrax irqi sp. nov. with adultindividuals of the Neogene clade Pachyrukhinae, indicates possibleheterochronic (paedomorphic) traits in the later forms.@font-face{font-family:"ＭＳ 明朝";mso-font-charset:78;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:1 134676480 16 0 131072 0;}@font-face{font-family:"Cambria Math";panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:3 0 0 0 1 0;}@font-face{font-family:Cambria;panose-1:2 4 5 3 5 4 6 3 2 4;mso-font-charset:0;mso-generic-font-family:auto;mso-font-pitch:variable;mso-font-signature:-536870145 1073743103 0 0 415 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal{mso-style-unhide:no;mso-style-qformat:yes;mso-style-parent:"";margin:0cm;margin-bottom:.0001pt;mso-pagination:widow-orphan;font-size:11.0pt;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:Cambria;mso-fareast-theme-font:minor-latin;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-ansi-language:ES-AR;mso-fareast-language:EN-US;}.MsoChpDefault{mso-style-type:export-only;mso-default-props:yes;font-family:Cambria;mso-ascii-font-family:Cambria;mso-ascii-theme-font:minor-latin;mso-fareast-font-family:"ＭＳ 明朝";mso-fareast-theme-font:minor-fareast;mso-hansi-font-family:Cambria;mso-hansi-theme-font:minor-latin;mso-bidi-font-family:"Times New Roman";mso-bidi-theme-font:minor-bidi;mso-fareast-language:JA;}div.WordSection1{page:WordSection1;}