Phyllodon

Taxobox
name = "Phyllodon"
status = fossil
fossil_range = Late Jurassic
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Cerapoda
infraordo = Ornithopoda
familia = ?Hypsilophodontidae
genus = "Phyllodon"
binomial = "Phyllodon henkeli"
binomial_authority = Thulborn, 1973

"Phyllodon" (meaning "leaf tooth") was a genus of small ornithopod dinosaur from the Kimmeridgian-age Upper Jurassic Guimarota Formation of Leiria, Portugal.

This genus is known from teeth and possibly partial lower jaws. The name [http://species.wikimedia.org/wiki/List_of_valid_homonyms_3 is also in use] for a genus of modern moss, but this is not considered to be a problem because the two organisms are in two different kingdoms. The "Phyllodon" genus may have been closely related to contemporaneous dinosaurs in North America.

History

"Phyllodon" is based on MGSP G5, a partial lower jaw tooth recovered from a lignite marl in a mine near the city of Leiria. Richard Thulborn, who described the genus, added an upper beak tooth (MGSP G2). He regarded the new genus as a hypsilophodontid, and presented a conjectural restoration of the tooth arrangement.cite journal |last=Thulborn |first=Richard A. |year=1973 |title=Teeth of ornithischian dinosaurs from the Upper Jurassic of Portugal, with description of a hypsilophodontid ("Phyllodon henkeli" gen. et sp. nov.) from the Guimarota lignite. |journal=Memória Serivoços Geológicos de Portugal (Nova Série) |volume=22 |pages=89–134 ] Peter Galton, reviewing Late Jurassic North American hypsilophodontids a few years later, found that the "Phyllodon" teeth best matched those of "Nanosaurus", and agreed with a hypsilophodontid identity because the lower jaw tooth is asymmetric in front and back views.cite journal |last=Galton |first=Peter M. |authorlink=Peter Galton |year=1983 |title=The cranial anatomy of "Dryosaurus", a hypsilophodontid dinosaur from the Upper Jurassic of North America and East Africa, with a review of hypsilophodontids from the Upper Jurassic of North America |journal=Geologica et Palaeontologica |volume=17 |pages=207–243 ]

Because of the sparse material, "Phyllodon" has often been tossed off as a dubious basal ornithopod of uncertain affinities.cite book |last=Sues |first=Hans-Dieter |coauthors=and Norman, David B. |editor= Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=1st |year=1990 |publisher=University of California Press |location=Berkeley |isbn=0-520-06727-4 |pages=498-509 |chapter=Hypsilophodontidae, "Tenontosaurus", Dryosauridae] cite book |last=Norman |first=David B. |authorlink=David B. Norman |coauthors=Sues, Hans-Dieter; Witmer, Larry M.; and Coria, Rodolfo A. |editor=Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.)|title=The Dinosauria |edition=2nd |year= 2004|publisher=University of California Press |location=Berkeley |isbn=0-520-24209-2 |pages=393-412 |chapter=Basal Ornithopoda] However, more material that might belong to this genus has been recovered from the original locality and described. Included in this material are over 120 more teeth from all parts of the jaw and four partial lower jaws with the teeth lost. Oliver Rauhut, who described the new material, tentatively identified the lower jaws as "Phyllodon" due to there being no other similar dinosaurs found at the locality. The teeth were very small (up to 3 millimeters across, or 0.1 inches) and possibly juvenile. He also found additional diagnostic characteristics for "Phyllodon" in the new material, including very tall upper jaw teeth, indicating that it could be a valid genus after all. After comparing it to other hypsilophodonts, he found that it best matched the roughly contemporaneous "Drinker" of the North American Morrison Formation, with various details suggesting that they were closely related.cite journal |last=Rauhut |first=Oliver W.M. |year=2001 |title=Herbivorous dinosaurs from the Late Jurassic (Kimmeridgian) of Guimarota, Portugal |journal=Proceedings of the Geologists' Association |volume=112 |pages=275–283 ] Similarly, Galton found its teeth to be similar to those of "Drinker" and "Nanosaurus" in his 2006 review.cite book |last=Galton |first=Peter M. |authorlink=Peter Galton |editor= Carpenter, Kenneth (ed.) |title=Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs |year=2006 |publisher=Indiana University Press |location=Bloomington and Indianapolis |isbn=0-253-34817-X |pages=17-47 |chapter=Teeth of ornithischian dinosaurs (mostly Ornithopoda) from the Morrison Formation (Upper Jurassic) of the western United States ]

Paleobiology

As a hypsilophodontid or other basal ornithopod, "Phyllodon" would have been a bipedal herbivore. Its size has not been estimated, but as most adult hypsilophodonts were 1-2 meters long (3.3-6.6 feet), this genus would probably have been of similar size. Its similarity to the North American "Drinker" and "Nanosaurus" is another piece of evidence linking Late Jurassic Portuguese dinosaur faunas with the contemporaneous Morrison Formation dinosaurs.cite book|title=Paleontology and Geology of the Upper Morrison Formation|year=2006|chapter=Late Jurassic dinosaurs from the Morrison Formation (USA), the Lourinhã and Alcobaça Formations (Portugal), and the Tendaguru Beds (Tanzania): a comparison |editor=Foster, John R.; and Lucas, Spencer G. (eds.) |author=Mateus, Octávio |pages=223-231 |publisher=New Mexico Museum of Natural History and Science |location=Albuquerque, New Mexico |series=New Mexico Museum of Natural History and Science Bulletin (36) ]

References

External links

* [http://www.users.qwest.net/~jstweet1/ornithopoda.htm "Phyllodon"] on "Thescelosaurus"!, under Ornithopoda "i.s."