''Galleonosaurus'' (meaning " galleon lizard" as the upper jaw bone resembles an upturned galleon) is a genus of basal

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

dinosaur from the Wonthaggi Formation of the Gippsland region of Victoria,

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

and only species is ''Galleonosaurus dorisae''.

Discovery and naming

The original specimen that would form the basis for ''Galleonosaurus'' was discovered at the Flat Rocks locality of the Wonthaggi Formation in 2008 by palaeontologist Gerry Kool. This was the same site that the related ''

Qantassaurus ''Qantassaurus'' ( ) is a genus of basal two-legged, plant-eating elasmarian ornithischian dinosaur that lived in Australia about 125-112 million years ago, when the continent was still partly south of the Antarctic Circle. It was described b ...

'', named twenty years earlier in 1999, had been found.Poropat, S
Galleono-saurus: A Flat Rocks Dinosaur.
Dinosaur Dreaming 2019 Field Report, 20. Flat Rocks is thought to have been deposited 125 million years ago in the late Barremian age of the Cretaceous, and is today located near Inverloch, Victoria within the

Bunurong Marine National Park The Bunurong Marine National Park () is a protected marine national park located off the coast of Cape Paterson in the South Gippsland region of Victoria, Australia. The marine national park is located about southwest of and about off the ...

, on a shoreline rock platform. During the Cretaceous, the area would've been at a far higher latitude, within the Antarctic Circle. After discovery, specimen was catalogued at the Melbourne Museum and studied by Matthew C. Herne. He and colleagues would go on to name the specimen as ''Galleonosaurus dorisae'' in 2019, in a paper published in the '' Journal of Paleontology''. It is the fifth named ornithopod from Victoria, following ''

Atlascopcosaurus ''Atlascopcosaurus'' () is a genus of herbivorous basal iguanodont dinosaur from the Early Cretaceous of the present Australia. Classification The type specimen, NMV P166409, was found in 1984 at the Dinosaur Cove East site at the coast of ...

'', '' Leaellynasaura'', ''Qantassaurus'', and ''

Diluvicursor ''Diluvicursor'' ("flood runner") is a genus of small ornithischian from the Lower Albian (Early Cretaceous) of Australia. It is known from one species, the type species ''D. pickeringi''. The two known specimens, a vertebra and a partial juveni ...

''. The generic name is derived from "galleon" (a type of large sailing ship) and "saurus" (New Latin from the Greek sauros for lizard), in reference to the appearance of the maxilla to the upturned hull of a galleon. The specific name ''dorisae'' was given in recognition of Doris Seegets-Villiers for her geological, palynological, and taphonomic work on the Flat Rocks fossil vertebrate locality. The holotype specimen is NMV P229196, a complete left maxilla with partial dentition. In addition to this specimeen, several other specimens from Flat Rocks were referred to ''Galleonosaurus''. These include: NMV P212845, a partial left maxilla lacking erupted dentition; NMV P208178, a partial left maxilla with erupted dentition; NMV P208113, a worn right maxillary tooth; NMV P208523, worn left maxillary tooth; and NMV P209977, partial left maxilla, lacking erupted dentition. In addition, the specimen NMV P186440, collected from the nearby locality The Caves, was referred to the taxon. It consists of a posterior portion of left maxilla, left palatine, and fragment of left lacrimal.

Description

''Galleonosaurus'' would've been a small, bipedal animal. It is characterized by five potential autapomorphies: ascending ramus of the has two slot-like on the anterior (front) margin that communicate with the neurovascular tract; neurovascular tract bifurcates internally to exit at two anteroventral (front, on the bottom) maxillary foramina; lingual (inner) margin of maxillary tooth roots in midregion of tooth row form an S-bend at their bases; posterior third of maxilla on some, but not all, specimens deflects posterolaterally (backwards, to the side) at an abrupt kink; and lateral end of lateral ramus forms a hatchet-shaped flange. Part of the bone is known, but unlike the maxilla it is too fragmented to determine much of its anatomy. Among the known specimens of ''Galleonosaurus'', a small degree of variation has been observed. Some specimens including the holotype have fifteen alveoli, or tooth positions, whereas others have thirteen or fourteen, though show indications of small or developing ones. The teeth themselves also demonstrate some variation, though it is only minor. Additionally, an abrupt kink in the jawbone is present on some but all specimens; likewise, one specimen has a pyramid-shaped peak on the top edge, whereas the others are smooth and rounded in this area. The latter two traits do not differ along lines of age, and so it has been suggested it may represent evidence of subspecific variation in the species or sexual dimorphism. Neither hypothesis, however, can be clearly tested, leaving the nature of the morphological variation unclear.

Phylogeny

To assess the phylogenetic position of ''Galleonosaurus'', Herne ''et al.'' used a data matrix from a 2016 paper by Paul-Emile Dieudonné and colleagues. However, due to the fragmentary nature of the Victorian taxa of interest, they extensively revised the dataset so as to have heightened chances of good resolution in the results. Numerous characters (i.e. anatomical data points) were removed, altered, or added. The analysis found ''Galleonosaurus'' to be a member of the clade

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".Madzia, Daniel; Boyd, Clint A.; Mazuch, Marti ...

, being related to other Gondwanan ornithopods. This result was supported by the observation of multiple shared anatomical traits between the elasmarian taxa. The material proved too fragmentary, however, to resolve more precise relationships between these species, though dental similarities indicate a potential close relationship to ''Leaellynasaura'' and ''Atlascopcosaurus''. It has been noted to be possible that ''Galleonosaurus dorisae'' may be a

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''Qantassaurus intrepidus'' rather than a distinct taxon, given they are known from non-overlapping remains and are from the same locality. However, dentaries from Flat Rocks have been discovered which different from that of ''Qantassaurus'', having been termed Victoria Ornithopod Dentary morphotype 3, or VOD3; these confirm the presence of multiple small ornithopods in the ecosystem. Compared to the short dentary of ''Qantassaurus'', the VOD3 dentaries are more elongated, and have more positions, with thirteen as opposed to ten. Seeing as the ''Galleonosaurus'' maxillae have fifteen positions, and ornithopod dentaries and maxillae of the same species generally only differ in this number by up to two, it was considered unlikely that the ''Qantassaurus'' dentaries rather than the VOD3 ones belong to the same animal as ''Galleonosaurus''. Despite this, no definite referral of the VOD3 material to ''Galleonosaurus'' could be made. The cladogram below shows results from the analysis by Herne ''et al.'', 2019:

References

Ornithopods Barremian life Early Cretaceous dinosaurs of Australia Fossils of Australia Fossil taxa described in 2019 Ornithischian genera {{ornithopod-stub