Elasmaria

Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".

Elasmarians Temporal range: Cretaceous,
Anabisetia
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Neornithischia
Clade:	†Ornithopoda
Clade:	†Elasmaria Calvo, Porfiri, and Novas, 2007
Genera
†Anabisetia †Atlascopcosaurus †Chakisaurus †Diluvicursor †Fostoria? †Fulgurotherium †Galleonosaurus †Gasparinisaura †Isasicursor †Iyuku? †Kangnasaurus? †Leaellynasaura †Macrogryphosaurus †Mahuidacursor †Morrosaurus †Muttaburrasaurus? †Notohypsilophodon †Qantassaurus †Sektensaurus †Talenkauen †Tietasaura †Trinisaura †Weewarrasaurus

Classification

Calvo et al. (2007) coined Elasmaria to accommodate Macrogryphosaurus and Talenkauen, which they recovered as basal iguanodonts distinct from other iguanodontians in having mineralized plates on the ribs. In 2016, a paper describing the genus Morrosaurus found Elasmaria to be far larger than its initial contents of two taxa, instead containing a variety of ornithopods from the Southern Hemisphere. In 2021, under the Phylocode, Madzia et al. (2021) formally defined Elasmaria as "the smallest clade containing Macrogryphosaurus gondwanicus and Talenkauen santacrucensis, provided that it does not include Hypsilophodon foxii, Iguanodon bernissartensis, or Thescelosaurus neglectus. Fonseca et al. (2024) redefined Elasmaria as "the largest clade containing Macrogryphosaurus gondwanicus and Talenkauen santacrucensis but not Dryosaurus altus, Hypsilophodon foxii, Iguanodon bernissartensis, and Thescelosaurus neglectus" so that it included more related taxa. The cladogram below follows their preferred reference phylogeny, taken from the results of their own study.

Ornithopoda

Hypsilophodontidae Gideonmantellia amosanjuanae Hypsilophodon foxii Iguanodontia Rhabdodontomorpha Euiguanodontia Callovosaurus leedsi Dryomorpha Dryosauridae Elrhazosaurus nigeriensis Valdosaurus canaliculatus Eousdryosaurus nanohallucis Dysalotosaurus lettowvorbecki Dryosaurus altus Dryosaurus elderae CM 1949 Draconyx loureiroi Oblitosaurus bunnueli Camptosauridae Camptosaurus dispar Uteodon aphanoecetes Styracosterna Cumnoria prestwichii Owenodon hoggii Hippodraco scutodens Ouranosaurus nigeriensis Iguanodon bernissartensis Hadrosauroidea Elasmaria Iyuku raathi Weewarrasaurus pobeni Kangnasaurus coetzeei Anabisetia saldiviai Diluvicursor pickeringi Notohypsilophodon comodorensis Trinisaura santamartaensis Gasparinisaura cincosaltensis Galleonosaurus dorisae Mahuidacursor lipanglef Morrosaurus antarcticus Atlascopcosaurus loadsi Qantassaurus intrepidus Fostoria dhimbangunmal Isasicursor santacrucensis Muttaburrasaurus langdoni Talenkauen santacrucensis Sektensaurus sanjuanboscoi Leaellynasaura amicagraphica Macrogryphosaurus gondwanicus