Phyllodon
Encyclopedia
Phyllodon was a genus
of small ornithopod
dinosaur
from the Kimmeridgian
-age Upper Jurassic Guimarota Formation of Leiria, Portugal
. It may have been closely related to contemporaneous dinosaurs in North America
.
This genus is known from teeth
and possibly partial lower jaws
. The name 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
.
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 hypsilophodont
id, and presented a conjectural restoration of the tooth arrangement. 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.
Because of the sparse material, Phyllodon has often been tossed off as a dubious
basal
ornithopod of uncertain affinities. 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. Similarly, Galton found its teeth to be similar to those of Drinker and Nanosaurus in his 2006 review.
. 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 fauna
s with the contemporaneous Morrison Formation dinosaurs.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of small ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs 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, and dominated the North American...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from the Kimmeridgian
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age or stage in the Late or Upper Jurassic epoch or series. It spans the time between 155.7 ± 4 Ma and 150.8 ± 4 Ma . The Kimmeridgian follows the Oxfordian and precedes the Tithonian....
-age Upper Jurassic Guimarota Formation of Leiria, Portugal
Portugal
Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...
. It may have been closely related to contemporaneous dinosaurs in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
.
This genus is known from teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
and possibly partial lower jaws
Mandible
The mandible pronunciation or inferior maxillary bone forms the lower jaw and holds the lower teeth in place...
. The name is also in use for a genus of modern moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
, but this is not considered to be a problem because the two organisms are in two different kingdoms
Kingdom (biology)
In biology, kingdom is a taxonomic rank, which is either the highest rank or in the more recent three-domain system, the rank below domain. Kingdoms are divided into smaller groups called phyla or divisions in botany...
.
History
Phyllodon is based onHolotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
MGSP G5, a partial lower jaw tooth recovered from a lignite
Lignite
Lignite, often referred to as brown coal, or Rosebud coal by Northern Pacific Railroad,is a soft brown fuel with characteristics that put it somewhere between coal and peat...
marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
in a mine near the city of Leiria
Leiria
Leiria is a city in Leiria Municipality in the Centro Region, Portugal. It is the capital of Leiria District. The city proper has 50,200 inhabitants and the entire municipality has nearly 120,000...
. Richard Thulborn, who described the genus, added an upper beak
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
tooth (MGSP G2). He regarded the new genus as a hypsilophodont
Hypsilophodont
Hypsilophodonts were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1–2 meters long . They are known from Asia, Australia, Europe, New Zealand, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age...
id, and presented a conjectural restoration of the tooth arrangement. Peter Galton
Peter Galton
Peter M. Galton is a British vertebrate paleontologist working in America, who has to date written or co-written about a hundred papers in scientific journals or chapters in paleontology textbooks, especially on ornithischian and prosauropod dinosaurs.With Robert Bakker in a joint article...
, reviewing Late Jurassic North American hypsilophodontids a few years later, found that the Phyllodon teeth best matched those of Nanosaurus
Nanosaurus
Nanosaurus is the name given to a genus of dinosaur from the Late Jurassic. Described by Othniel Charles Marsh in 1877, it is a poorly-known ornithischian of uncertain affinities. Its fossils are known from the Morrison Formation of Colorado and possibly Wyoming...
, and agreed with a hypsilophodontid identity because the lower jaw tooth is asymmetric in front and back views.
Because of the sparse material, Phyllodon has often been tossed off as a dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
ornithopod of uncertain affinities. 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
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
. He also found additional diagnostic characteristics
Autapomorphy
In cladistics, an autapomorphy is a distinctive anatomical feature, known as a derived trait, that is unique to a given terminal group. That is, it is found only in one member of a clade, but not found in any others or outgroup taxa, not even those most closely related to the group...
for Phyllodon in the new material, including very tall upper jaw
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
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
Drinker
Drinker was a genus of hypsilophodont dinosaur from the late Jurassic period of North America. Although based on good remains, it remains obscure due to a lack of post-naming publications.-Description:...
of the North American Morrison Formation
Morrison Formation
The Morrison Formation is a distinctive sequence of Late Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish...
, with various details suggesting that they were closely related. Similarly, Galton found its teeth to be similar to those of Drinker and Nanosaurus in his 2006 review.
Paleobiology
As a hypsilophodontid or other basal ornithopod, Phyllodon would have been a bipedal herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. 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 fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...
s with the contemporaneous Morrison Formation dinosaurs.
External links
- Phyllodon on Thescelosaurus!, under Ornithopoda i.s.