Trimucrodon
Encyclopedia
Trimucrodon is a genus
of herbivorous
dinosaur
from the Late Jurassic
or Early Cretaceous
of what is now Portugal
. It has been classified as a basal
ornithischia
n, but is a nomen dubium
: it is a "tooth genus" known only from its teeth.
Between 1962 and 1967 German zoologist Georg Krusat uncovered mammal fossils near Porto Dinheiro
, Lourinha
, in layers of the Camadas de Alcobaça Formation. This rock unit was then seen as dating from the Kimmeridgian
stage
, around 150 to 155 million years ago but was later suggested to date to the Cretaceous (early Berriasian
stage), about 145 million years old. One small tooth was recognised by Richard A. Thulborn as dinosaurian instead of mammalian and in 1973 he described and named it Trimucrodon cuneatus; the paper was not published until 1975. The generic name is derived from Latin
tri~, "three", and mucro, "dagger point", and Greek odous, "tooth". The specific name means "wedge-shaped" in Latin. The holotype
tooth is part of the collection of the Lehrstuhl fur Paläontologie, Freie Universität at Berlin
but has no published inventory number. Some other Portuguese teeth from the formation were referred to the species.
Thulborne originally classified Trimucrodon as a member of the Fabrosauridae
. José Ignacio Ruiz-Omeñaca in 2001 placed it within the Heterodontosauridae
. However, recent authors have considered it a basal ornthischian of uncertain affiliations
.
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 herbivorous
Herbivore
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...
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 Late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
or Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
of what is now 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 has been classified as a 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:...
ornithischia
Ornithischia
Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
n, but is a nomen dubium
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
: it is a "tooth genus" known only from its teeth.
Between 1962 and 1967 German zoologist Georg Krusat uncovered mammal fossils near Porto Dinheiro
Porto Dinheiro
Porto Dinheiro is a locality in the county of Ribamar, municipality of Lourinhã, in Portugal.It is known as a rich fossil locality, from where were found many Late Jurassic dinosaurs and mammals...
, Lourinha
Lourinhã
Lourinhã is a municipality in Portugal with a total area of 147.2 km² and a total population of 24,601 inhabitants. The seat of the municipality is the village of Lourinhã, with a population of 8,800 inhabitants....
, in layers of the Camadas de Alcobaça Formation. This rock unit was then seen as dating 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....
stage
Faunal stage
In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.Rock...
, around 150 to 155 million years ago but was later suggested to date to the Cretaceous (early Berriasian
Berriasian
In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...
stage), about 145 million years old. One small tooth was recognised by Richard A. Thulborn as dinosaurian instead of mammalian and in 1973 he described and named it Trimucrodon cuneatus; the paper was not published until 1975. The generic name is derived from Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
tri~, "three", and mucro, "dagger point", and Greek odous, "tooth". The specific name means "wedge-shaped" in Latin. The holotype
Holotype
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...
tooth is part of the collection of the Lehrstuhl fur Paläontologie, Freie Universität at Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
but has no published inventory number. Some other Portuguese teeth from the formation were referred to the species.
Thulborne originally classified Trimucrodon as a member of the Fabrosauridae
Fabrosauridae
The Fabrosauridae was originally proposed by Galton , as a group of basal ornithischian dinosaurs from the Early to Middle Jurassic. However, recent studies indicate the Fabrosaurs are not a natural grouping of dinosaurs, and instead consist of unrelated genera.The proposed "Fabrosaurs" descended...
. José Ignacio Ruiz-Omeñaca in 2001 placed it within the Heterodontosauridae
Heterodontosauridae
Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal members of the group...
. However, recent authors have considered it a basal ornthischian of uncertain affiliations
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
.
External links
- Trimucrodon in the Dinosaur Encyclopedia at DinoRuss' Lair