2026-10-14T03:25:43Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34055918 2026-10-02T08:40:12Z category_24 category_272 category_39 category_734 portal_87 item_type_3 month_year_10_2026

A new albertosaurine from the Oldman Formation, Alberta, Canada, illuminates ambiguity between albertosaurine and tyrannosaurine characteristics Mark J. Powers (12112576) James G. Napoli (22531481) Colton C. Coppock (21792645) Henry S. Sharpe (18384921) Christiana W. Garros (18384927) Alexandre V. Demers-Potvin (7130471) Gorm S. Raun (25301585) Jordan C. Stock (25301588) Tetsuto Miyashita (309647) Philip J. Currie (9418829) Evolutionary Biology Environmental Sciences not elsewhere classified Ecology Biological Sciences not elsewhere classified taxon dataset recovers specimens previously attributed restricted stratigraphic overlap rapid character acquisition narrower pila promaxillaris modified recent character low diversity relative earliest diverging member recovery within albertosaurinae late cretaceous radiation tromerosaurus solumons </ gorgosaurus libratus </ late cretaceous tromerosaurus </ gorgosaurus </ teratophoneus </ lythronax </ daspletosaurus </ bistahieversor </ younger divergence tyrannosaurine characteristics tyrannosaurid species tyrannosaurid characteristics topologies along suggests uncertainty shares features results support prompts reassessment oldman formation offers support illuminates ambiguity high longevity derived tyrannosaurines contemporaneous megaherbivores bayesian inference anatomical diagnosis allowed referral <p>Tyrannosaurid species have often been considered to have high longevity and low diversity relative to contemporaneous megaherbivores. Recent chronospecies assertions around tyrannosaurid lineage evolution have reinforced this idea. An albertosaurine, <i>Tromerosaurus solumons</i>, from the Oldman Formation of Alberta, Canada, shares features with <i>Daspletosaurus</i> and <i>Gorgosaurus</i>, and prompts reassessment of tyrannosaurid characteristics and the Late Cretaceous radiation of Tyrannosauridae. Maxillary morphometrics reveal clear intermediate morphologies in <i>Tromerosaurus</i> between <i>Daspletosaurus</i> and <i>Gorgosaurus</i>, including an anteroposteriorly longer maxillary fenestra and narrower pila promaxillaris than in <i>Gorgosaurus libratus</i>. An anatomical diagnosis of <i>Tromerosaurus solumons</i> allowed referral of specimens previously attributed to <i>Gorgosaurus</i>. Restricted stratigraphic overlap between <i>Tromerosaurus</i> and <i>Gorgosaurus</i> offers support to this distinction. A modified recent character-taxon dataset recovers <i>Tromerosaurus</i> as the earliest diverging member of Albertosaurinae under parsimony or Tyrannosaurinae under Bayesian inference. The difference in topologies along with reduced node support values for clades such as <i>Lythronax</i> + <i>Teratophoneus</i>, or <i>Bistahieversor</i> and other derived tyrannosaurines, suggests uncertainty as to their recovery within Albertosaurinae or Tyrannosaurinae. Together, these results support a younger divergence of the two main tyrannosaurid lineages with rapid character acquisition and transition during the Late Cretaceous (Santonian–Maastrichtian).</p> 2026-10-02T08:40:12Z Dataset Dataset 10.6084/m9.figshare.34055918.v1 https://figshare.com/articles/dataset/A_new_albertosaurine_from_the_Oldman_Formation_Alberta_Canada_illuminates_ambiguity_between_albertosaurine_and_tyrannosaurine_characteristics/34055918 CC BY 4.0