Lambeosaurinae

Lambeosauridae /ˌlæmbiəˈsɔːraɪniː/ (meaning 'lambe's lizards') is an extinct group of crested hadrosauroid dinosaurs.

Description

Size

Uncertainty surrounds the size of lambeosaurs from the European continent. Hadrosaurs found there, alongside other dinosaurs, have traditionally been considered representatives of the phenomenon of insular dwarfism, as the continent was then made up of many smaller islands. Many fossil remains from the continent are smaller than those of hadrosaurs found elsewhere in the world, with only isolated remains indicating individuals of adult size by the standards of their relatives in North America and Asia. It remains possible, however, that at least some cases instead represent misidentification of juvenile remains.Dalla Vecchia, F. M. (2014). An overview of the latest Cretaceous hadrosauroid record in Europe. Hadrosaurs, 268-297.Dalla Vecchia FM, Gaete R, Riera V, Oms O, Prieto-Márquez A, Vila B, et al. The hadrosauroid record in the Maastrichtian of the eastern Tremp Syncline (northern Spain). In: Eberth DA, Evans DC, editors. Hadrosaurs. Bloomington: Indiana University Press; 2014. pp. 298–314 The presence of genuine dwarfed taxa has been validated in some cases; adults of the genus '' Minqaria'', for example, are thought to be around in length. Contrastingly, the genus ''Pararhabdodon'' has a projected adult size similar to those of hadrosaurs on other continents, and known remains of '' Adynomosaurus'' and hadrosaurs from the Basturs Poble bonebed are of this adult size themselves. Why hadrosaurs of such variable sizes co-exist, despite being subject to the same environmental pressures, remains unclear.Cruzado Caballero, P., & Canudo, J. (2015). Presence of diminutive hadrosaurids (Dinosauria: Ornithopoda) in the Maastrichtian of the south-central Pyrenees (Spain). Journal of Iberian Geology, 41(1), 71-81.

Classification

History

The first material of hadrosaurids were found in the 1850s and named by American paleontologist Joseph Leidy: ''Trachodon mirabilis'' from Montana and '' Thespesius occidentalis'' from South Dakota in 1856, and '' Hadrosaurus foulkii'' from New Jersey in 1859. Numerous additional genera and species were described throughout the following decades, with the first discoveries in Alberta in the late 1890s and early 1900s by Canadian paleontologist Lawrence M. Lambe being ascribed to '' Trachodon'' under the subgenus '' Pteropelyx''. The first hadrosaur to preserve a crest on the skull was ''Saurolophus'' named in 1912 by American paleontologist Barnum Brown for a skeleton from Alberta. It was to ''Saurolophus'' that Lambe found the greatest similarities for new specimens described from Alberta in 1914, which preserved a prominent crest on top of the skull. These remains he assigned to '' Stephanosaurus'', a new genus name for '' Trachodon marginatus'' he had named earlier for material from the 1900s expeditions. While the crest of ''Saurolophus'' projected backwards, that of the material assigned to ''Stephanosaurus'' projected upwards above the eye. Brown followed up in 1914 with the description of some nearly complete skeletons from Alberta that he named '' Corythosaurus casuarius'', which showed a tall and rounded crest atop the skull, and with him questioning the generic status of ''Stephanosaurus''. As ''Stephanosaurus marginatus'' was named for incomplete material from the skeleton, Brown did not find the referral of the crested skulls to the taxon justifiable, suggesting they could belong to the genus ''Corythosaurus'' but as a distinct species. Brown also separated Trachodontidae into two subfamilies for the first time, uniting the taxa with crested skulls into Saurolophinae while other genera were contained within Trachodontinae.

Lambe subsequently revised the classification of Hadrosauridae (the older name for Trachodontidae) in 1920 following the description of the new genera '' Cheneosaurus'', ''Edmontosaurus'', and ''Prosaurolophus'' and the discovery of a new skull he referred to ''Stephanosaurus'' in the interim, identifying that the crests of ''Saurolophus'' and ''Prosaurolophus'' were formed of different bones than the other crested genera and as a result separating ''Corythosaurus'', ''Cheneosaurus'', ''Hypacrosaurus'' and ''Stephanosaurus'' (including the crested skulls) into the new subfamily Stephanosaurinae. In 1923 the crested skulls were again removed from ''Stephanosaurus'', this time by Canadian paleontologist William A. Parks, who established the new taxon '' Lambeosaurus lambei'' for them in honor of Lambe who had first described them. As ''Stephanosaurus'' could no longer be shown to be a crested hadrosaur, Parks also named the subfamily Lambeosaurinae to replace Stephanosaurinae for the group. This separation was further supported by American paleontologist Charles W. Gilmore the next year, who found that ''Stephanosaurus'' could be better referred to the genus '' Kritosaurus'' and was a member of Hadrosaurinae rather than Lambeosaurinae. Gilmore could not identify which subfamily ''Trachodon'' should belong in due to its very limited material, so he supported the separation of Hadrosauridae into Hadrosaurinae (rather than Trachodontinae), Saurolophinae, and Lambeosaurinae, the latter of which now also included ''Parasaurolophus''.

American paleontologists Richard Swann Lull and Nelda E. Wright published a review article of Hadrosauridae in 1942 where they supported the subfamilies of Gilmore with the addition of Cheneosaurinae, which they named for small-bodied crested genera ''Cheneosaurus'' and ''Procheneosaurus''. Cheneosaurins had small rounded crests while lambeosaurines possessed more elaborate crests of different forms between the genera. Both Lambeosaurinae and Cheneosaurinae were elevated to family rank as Lambeosauridae and Cheneosauridae by German paleontologist Friedrich von Huene in 1948 and 1956 respectively. However, American paleontologist Charles Mortram Sternberg in 1953 recognized that the divisions of previous studies were not useful, separating genera based on an arbitrary decision of feature significance, especially the separation of Cheneosaurinae from Lambeosaurinae. As a result, he condensed Hadrosauridae into only two subfamilies: Hadrosaurinae and Lambeosaurinae, with saurolophines being members of Hadrosaurinae, and cheneosaurines being members of Lambeosaurinae. Within Lambeosaurinae he included ''Lambeosaurus'', ''Corythosaurus'', ''Hypacrosaurus'', ''Parasaurolophus'', ''Cheneosaurus'', ''Tetragonosaurus'', and ''Trachodon''; a classification he reiterated in 1954.

Work by American paleontologist Peter Dodson in 1975 revised the taxonomy of Lambeosaurinae by recognizing that ''Cheneosaurus'' and ''Procheneosaurus'' were not distinct genera but rather juveniles of other taxa that were not old enough to have fully-developed crests. The species of ''Procheneosaurus'' were identified as synonyms of either ''Lambeosaurus'' or ''Corythosaurus'', while ''Cheneosaurus'' was identified as a juvenile of ''Hypacrosaurus''. Following the recognition of cheneosaurs as juveniles of ''Lambeosaurus'', ''Corythosaurus'', and ''Hypacrosaurus'', American palaeontologist Michael K. Brett-Surman published a phylogeny of all accepted genera of Hadrosauridae in 1979, and expanded Lambeosaurinae to also include '' Tsintaosaurus'', with ''Jaxartosaurus'' and ''Bactrosaurus'' as early members, and ''Lambeosaurus'', ''Corythosaurus'' and ''Hypacrosaurus'' as one another's closest relatives. A 1990 review of hadrosaurs by American paleontologists David B. Weishampel and John R. Horner was unable to conclude if ''Tsintaosaurus'' was a lambeosaurine or hadrosaurine, but added the Asian genera '' Barsboldia'' and ''Nipponosaurus'' to Lambeosaurinae. The content of Lambeosaurinae expanded over the next decades before the second review by Horner in 2004. During this period, the Asian genera ''Amurosaurus'', '' Charonosaurus'', and ''Olorotitan'' were named and added to Lambeosaurinae, and the status of ''Tsintaosaurus'' as a lambeosaurine was solidified.

Lambeosaurines have been traditionally split into the tribes or clades Parasaurolophini (''Parasaurolophus'', '' Charonosaurus'', others (?).) and Lambeosaurini (''Corythosaurus'', ''Hypacrosaurus'', ''Lambeosaurus'', others.). Corythosaurini (synonym of Lambeosaurini, see below) and Parasaurolophini as terms entered the formal literature in Evans and Reisz's 2007 redescription of ''Lambeosaurus magnicristatus''. Corythosaurini was defined as all taxa more closely related to ''Corythosaurus casuarius'' than to ''Parasaurolophus walkeri'', and Parasaurolophini as all those taxa closer to ''P. walkeri'' than to ''C. casuarius''. In this study, ''Charonosaurus'' and ''Parasaurolophus'' are parasaurolophins, and ''Corythosaurus'', ''Hypacrosaurus'', ''Lambeosaurus'', ''Nipponosaurus'', and '' Olorotitan'' are corythosaurins. However, later researchers pointed out that due to the rules of priority set forth by the ICZN, Any tribe containing ''Lambeosaurus'' is properly named Lambeosaurini, and that therefore the name "Corythosaurini" is a junior synonym, and the definition had ''Corythosaurus casuarius'' changed to ''Lambeosaurus lambei'', and the same for Parasaurolophini.Sullivan, R., Jasinski, S.E., Guenther, M. and Lucas, S.G. (2009). "The first lambeosaurin (Dinosauria, Hadrosauridae, Lambeosaurinae) from the Upper Cretaceous Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico." ''New Mexico Museum of Natural History and Science Bulletin'', 53: 405-417

In more recent years Tsintaosaurini ('' Tsintaosaurus'' + ''Pararhabdodon'') and Aralosaurini ('' Aralosaurus'' + ''Canardia'') have also emerged.

Subgroups

A 2013 study describing the genus ''Canardia'' found it to form a grouping with '' Aralosaurus'', therein named as Aralosaurini and defined as the most exclusive clade of hadrosaurs containing both ''Canardia'' and ''Aralosaurus''. Though one 2022 study recovered the tribe as monophyletic, most modern analyses fail to recover a natural grouping between the two genera. Daniel Madzia and colleagues registered the name under Phylocode in a 2021 study and redefined it as "the largest clade containing ''Aralosaurus tuberiferus'' and ''Canardia garonnensis'' but not ''Lambeosaurus lambei'', ''Parasaurolophus walkeri'', and ''Tsintaosaurus spinorhinus''".

Numerous members of the clade Lambeosaurinae are known from Europe, dating to the end of the Cretaceous period. These various named taxa have traditionally been found to group into numerous different lambeosaur lineages, including Aralosaurini, Tsintaosaurini, Lambeosaurini, and Parasaurolophini. However, a study by Nick Longrich and colleagues proposed European lambeosaurs to form a singular monophyletic group, therein named Arenysaurini, based upon a phylogenetic analysis incorporating data based on geographic origin. They phylogenetically defined the tribe as all hadrosaurids closer to '' Arenysaurus ardevoli'' than '' Tsintaosaurus spinorhinus'', '' Parasaurolophus walkeri'', or '' Lambeosaurus lambei''. In addition to the various named genera, indeterminate remains from across the continent including the Basturs Poble bonebed were proposed to represent arenysaurs.

The existence of a tsintaosaur clade of lambeosaurines was first recognized by palaeontologists Albert Prieto-Márquez and Johnathan R. Wagner, who in 2009 published a paper recognizing a phylogenetic relationship between '' Tsintaosaurus'' and ''Pararhabdodon'' based both on shared anatomical traits and a phylogenetic analysis. A 2013 study by Prieto-Márquez corroborated the existence of this grouping, and coined the tribe Tsintaosaurini to refer to it. The type genus is ''Tsintaosaurus'', and it was defined as the smallest clade containing ''Tsintaosaurus spinorhinus'' and ''Pararhabdodon isonensis''. Several studies since have corroborated the existence of the clade, though some others have failed to recover it, instead finding the two genera in a polytomy of basal lambeosaurs. A 2021 paper by Daniel Madzia and other ornithischian researchers, focused on a revising ornithischian nomenclature and converting existing group names into Phylocode-compliant clades, re-formalized the coining of Tsintaosaurini and revised its definition to be the most inclusive group including ''T. spinorhinus'' and ''P. isonensis'', but not '' Aralosaurus tuberiferus'', '' Lambeosaurus lambei'', or '' Parasaurolophus walkeri''. Longrich and colleagues instead consider the two genera unrelated, with ''Pararhabdodon'' being part of Arenysaurini.

The term Corythosaurini was first used by Brett-Surman in 1989, who characterized the taxon via reference to the premaxilary expansion into a hollow helmet-like cranial crest, as well as higher neural spines. The clade was formally defined via phylogenetic analysis by Evans and Reisz in 2007, and this was confirmed by multiple other analyses. In 2011, Sullivan et al. observed that by the rules of priority set by the International Code of Zoological Nomenclature, the name of the tribe ought to be Lambeosaurini due to its containing the defining type genus (''Lambeosaurus'') of its superior taxon (Lambeosaurinae). It is defined as all lambeosaurines closer to ''Lambeosaurus lambei'' than to ''Parasaurolophus walkeri'', ''Tsintaosaurus spinorhinus'', or ''Aralosaurus tuberiferus''.

Phylogeny

The following cladogram was recovered in a 2022 phylogenetic analysis by Xing Hai, and colleagues.

Distribution

Lambeosaurines originated on the continent of Laurasia during the Late Cretaceous, being initially found throughout modern Europe and Asia. Around the Campanian stage, lambeosaurines of the tribe Corythosauria colonized the landmass of Laramidia (modern western North America) via Beringia and spread as far south as Mexico, radiating into a diverse array of a body plans, including famous taxa such as ''Parasaurolophus'' and ''Lambeosaurus''. They appear to have also colonized the eastern landmass of Appalachia at some point, based on indeterminate lambeosaurine remains from the late Campanian/Maastrichtian-aged Kanguk Formation of Nunavut.

For unknown reasons, lambeosaurines largely disappeared from North America around the Campanian/Maastrichtian boundary (the last remaining confirmed American member being ''Hypacrosaurus''), but continued their dominance in Laurasia up to the end of the Cretaceous, with some members such as '' Ajnabia'' and '' Minqaria'' even colonizing northern Africa from Europe. However, fragmentary remains, including a partial humerus, resembling those of lambeosaurines have been reported from the late Maastrichtian-aged New Egypt Formation of New Jersey, USA. If these are lambeosaurine remains, these specimens are unique both for representing one of the very few records of lambeosaurines from the landmass of Appalachia (suggesting that lambeosaurines had managed to migrate eastwards to Appalachia during the Maastrichtian, following the partial closure of the Western Interior Seaway), and potentially representing one of the latest records of the group from North America.

See also

* Timeline of hadrosaur research

References

{{Taxonbar, from=Q135620

Dinosaur subfamilies
Late Cretaceous dinosaurs