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Supplementary cranial description of the types of Edmontosaurus regalis (Ornithischia: Hadrosauridae), with comments on the phylogenetics and biogeography of Hadrosaurinae

View Article: PubMed Central - PubMed

ABSTRACT

The cranial anatomy of the flat-skulled hadrosaurine Edmontosaurus regalis (Ornithischia: Hadrosauridae) is extensively described here, based on the holotype and paratype collected from the middle part of the Horseshoe Canyon Formation in southern Alberta. Focus is given to previously undocumented features of ontogenetic and phylogenetic importance. This description facilitates overall osteological comparisons between E. regalis and other hadrosaurids (especially E. annectens), and revises the diagnosis of E. regalis, to which a new autapomorphy (the dorsal half of the jugal anterior process bearing a sharp posterolateral projection into the orbit) is added. We consider the recently named Ugrunaaluk kuukpikensis from the upper Campanian/lower Maastrichtian of Alaska a nomen dubium, and conservatively regard the Alaskan material as belonging to Edmontosaurus sp.. A phylogenetic analysis of Hadrosauroidea using maximum parsimony further corroborates the sister-taxon relationship between E. regalis and E. annectens. In the strict consensus tree, Hadrosaurus foulkii occurs firmly within the clade comprising all non-lambeosaurine hadrosaurids, supporting the taxonomic scheme that divides Hadrosauridae into Hadrosaurinae and Lambeosaurinae. Within Edmontosaurini, Kerberosaurus is posited as the sister taxon to the clade of Shantungosaurus + Edmontosaurus. The biogeographic reconstruction of Hadrosaurinae in light of the time-calibrated cladogram and probability calculation of ancestral areas for all internal nodes reveals a significantly high probability for the North American origin of the clade. However, the Laramidia–Appalachia dispersals around the Santonian–Campanian boundary, inferred from the biogeographic scenario for the North American origin of Hadrosaurinae, are in conflict with currently accepted paleogeographic models. By contrast, the Asian origin of Hadrosaurinae with its relatively low probability resulting from the biogeographic analysis is worth seriously considering, despite the lack of fossil material from the Santonian and lower Campanian of Asia. Extra fossil collecting in appropriate geographic locations and stratigraphic intervals of Asia and Europe will help to clarify the biogeographic dynamics of hadrosaurine dinosaurs in the near future.

No MeSH data available.


Related in: MedlinePlus

Strict consensus of 24 most parsimonious trees resulting from the maximum parsimony analysis of Hadrosauroidea, showing the sister-group relationship between Hadrosaurinae and Lambeosaurinae within Hadrosauridae.Numbers above lines represent bootstrap proportions, whereas those below lines represent Bremer decay values. Bootstrap proportions lower than 20 and Bremer decay values less than 2 are not shown.
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pone.0175253.g020: Strict consensus of 24 most parsimonious trees resulting from the maximum parsimony analysis of Hadrosauroidea, showing the sister-group relationship between Hadrosaurinae and Lambeosaurinae within Hadrosauridae.Numbers above lines represent bootstrap proportions, whereas those below lines represent Bremer decay values. Bootstrap proportions lower than 20 and Bremer decay values less than 2 are not shown.

Mentions: A phylogenetic analysis of Hadrosauroidea resulted in 24 most parsimonious trees (MPTs) of 1037 steps, each with a consistency index of 0.476 and a retention index of 0.856. The strict consensus of the recovered MPTs reveals that the sister taxon to Lambeosaurinae consists of Brachylophosaurini, Kritosaurini, Saurolophini and Edmontosaurini, as well as Hadrosaurini that is solely represented by the enigmatic Hadrosaurus foulkii (Fig 20). In other words, H. foulkii is found to be firmly within the monophyletic group comprising all non-lambeosaurine hadrosaurids. Thus, we agree with the taxonomic scheme of Hadrosauridae both argued by Lull and Wright [7] and Sereno [5], where Hadrosauridae is divided into two clades, namely Hadrosaurinae and Lambeosaurinae. H. foulkii, Brachylophosaurini, and the clade of Kritosaurini + (Saurolophini + Edmontosaurini) form an unresolved polytomy at the base of Hadrosaurinae.


Supplementary cranial description of the types of Edmontosaurus regalis (Ornithischia: Hadrosauridae), with comments on the phylogenetics and biogeography of Hadrosaurinae
Strict consensus of 24 most parsimonious trees resulting from the maximum parsimony analysis of Hadrosauroidea, showing the sister-group relationship between Hadrosaurinae and Lambeosaurinae within Hadrosauridae.Numbers above lines represent bootstrap proportions, whereas those below lines represent Bremer decay values. Bootstrap proportions lower than 20 and Bremer decay values less than 2 are not shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383305&req=5

pone.0175253.g020: Strict consensus of 24 most parsimonious trees resulting from the maximum parsimony analysis of Hadrosauroidea, showing the sister-group relationship between Hadrosaurinae and Lambeosaurinae within Hadrosauridae.Numbers above lines represent bootstrap proportions, whereas those below lines represent Bremer decay values. Bootstrap proportions lower than 20 and Bremer decay values less than 2 are not shown.
Mentions: A phylogenetic analysis of Hadrosauroidea resulted in 24 most parsimonious trees (MPTs) of 1037 steps, each with a consistency index of 0.476 and a retention index of 0.856. The strict consensus of the recovered MPTs reveals that the sister taxon to Lambeosaurinae consists of Brachylophosaurini, Kritosaurini, Saurolophini and Edmontosaurini, as well as Hadrosaurini that is solely represented by the enigmatic Hadrosaurus foulkii (Fig 20). In other words, H. foulkii is found to be firmly within the monophyletic group comprising all non-lambeosaurine hadrosaurids. Thus, we agree with the taxonomic scheme of Hadrosauridae both argued by Lull and Wright [7] and Sereno [5], where Hadrosauridae is divided into two clades, namely Hadrosaurinae and Lambeosaurinae. H. foulkii, Brachylophosaurini, and the clade of Kritosaurini + (Saurolophini + Edmontosaurini) form an unresolved polytomy at the base of Hadrosaurinae.

View Article: PubMed Central - PubMed

ABSTRACT

The cranial anatomy of the flat-skulled hadrosaurine Edmontosaurus regalis (Ornithischia: Hadrosauridae) is extensively described here, based on the holotype and paratype collected from the middle part of the Horseshoe Canyon Formation in southern Alberta. Focus is given to previously undocumented features of ontogenetic and phylogenetic importance. This description facilitates overall osteological comparisons between E. regalis and other hadrosaurids (especially E. annectens), and revises the diagnosis of E. regalis, to which a new autapomorphy (the dorsal half of the jugal anterior process bearing a sharp posterolateral projection into the orbit) is added. We consider the recently named Ugrunaaluk kuukpikensis from the upper Campanian/lower Maastrichtian of Alaska a nomen dubium, and conservatively regard the Alaskan material as belonging to Edmontosaurus sp.. A phylogenetic analysis of Hadrosauroidea using maximum parsimony further corroborates the sister-taxon relationship between E. regalis and E. annectens. In the strict consensus tree, Hadrosaurus foulkii occurs firmly within the clade comprising all non-lambeosaurine hadrosaurids, supporting the taxonomic scheme that divides Hadrosauridae into Hadrosaurinae and Lambeosaurinae. Within Edmontosaurini, Kerberosaurus is posited as the sister taxon to the clade of Shantungosaurus + Edmontosaurus. The biogeographic reconstruction of Hadrosaurinae in light of the time-calibrated cladogram and probability calculation of ancestral areas for all internal nodes reveals a significantly high probability for the North American origin of the clade. However, the Laramidia–Appalachia dispersals around the Santonian–Campanian boundary, inferred from the biogeographic scenario for the North American origin of Hadrosaurinae, are in conflict with currently accepted paleogeographic models. By contrast, the Asian origin of Hadrosaurinae with its relatively low probability resulting from the biogeographic analysis is worth seriously considering, despite the lack of fossil material from the Santonian and lower Campanian of Asia. Extra fossil collecting in appropriate geographic locations and stratigraphic intervals of Asia and Europe will help to clarify the biogeographic dynamics of hadrosaurine dinosaurs in the near future.

No MeSH data available.


Related in: MedlinePlus