Vallesaurus
Encyclopedia
Vallesaurus is an extinct genus
of Late Triassic
elyurosaur drepanosauromorph. First found in Northern Italy
in 1975, it is one of the most primitive drepanosaurs. V. cenenis is the type species
, named in 2006. A second species, V. zorzinensis, was named in 2010.
, Italy. The genus was named in respect of professor Valle, the former director of the museum. The species, on the other hand, was named after a local municipality called Cene
neighbouring the site where the fossil was excavated. The specimen was given to palaeontologist Rupert Wild to study at the Staatliches Museum of Stuttgart
, Germany
. Wild named the genus and the type species in 1991
, but without describing it formally or providing the holotype specimen. Pinna (1993) provided the holotype and described it but the name "Vallesaurus" was considered a nomen nudum
. Renesto and Binelli named formally the genus and the type species in 2006
.
The second species, V. zorzinensis, was found in the same location and identified from the specimen MCSNB 4783. The specific name referred to the Zorzino Limestone Formation, where the holotype was found.
. Its tarsus
has a centrale
, or an ankle bone which articulates with the tibia
. In addition, Vallesaurus also has modified distal tarsals
and metatarsals, and a clawless hallux
.
Vallesaurus differs in some characteristics from another drepanosaur, Megalancosaurus
. Vallesaurus has a proportionally shorter and higher snout, a thicker and larger maxilla
and set of maxillary teeth, and a shorter cervical vertebra. It also lacks the fusion between the neural spines of the second and third dorsal vertebrae. Vallesaurus differs from Drepanosaurus
, another drepanosaur, in that it lacks the enormous claw found on the second digit of the manus
. It can be distinguished from Drepanosaurus, Megalancosaurus and possibly Dolabrosaurus
in the lack of a terminal spine at the end of the tail. In addition, Vallesaurus also differs from Hypuronector, a related drepanosaur, in having anteroposteriorly extended neural spines of the anterior dorsal vertebrae and forelimbs much shorter than the hindlimbs.
Vallesaurus as well as other drepanosaurids possess a fussed-like structure in the anterior dorsal region and highly modified cervical vertebrae with adaptations that limited lateral mobility. Both structures indicate the presence of powerful muscles and ligaments for the extension of the neck. This possibly suggests a projectile feeding adaptation. The head was suddenly launched forward to catch prey and the limited lateral mobility prevented undesired jerks of the neck which could have dislocated the cervical vertebrae during the quick extension. In smaller drepanosaurids like Megalancosaurus and Vallesaurus, such adaptations may be related to an insectivorous diet. The teeth of Vallesaurus seem well suited to cut or crush the tough exoskeleton
of insect
s and other arthropod
s.
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 Late Triassic
Late Triassic
The Late Triassic is in the geologic timescale the third and final of three epochs of the Triassic period. The corresponding series is known as the Upper Triassic. In the past it was sometimes called the Keuper, after a German lithostratigraphic group that has a roughly corresponding age...
elyurosaur drepanosauromorph. First found in Northern Italy
Northern Italy
Northern Italy is a wide cultural, historical and geographical definition, without any administrative usage, used to indicate the northern part of the Italian state, also referred as Settentrione or Alta Italia...
in 1975, it is one of the most primitive drepanosaurs. V. cenenis is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, named in 2006. A second species, V. zorzinensis, was named in 2010.
Nomenclature
The first specimen of Vallesaurus cenensis, MCSNB 4751, was found in 1975 by the staff of the Museo Civico di Scienze Naturali of BergamoBergamo
Bergamo is a town and comune in Lombardy, Italy, about 40 km northeast of Milan. The comune is home to over 120,000 inhabitants. It is served by the Orio al Serio Airport, which also serves the Province of Bergamo, and to a lesser extent the metropolitan area of Milan...
, Italy. The genus was named in respect of professor Valle, the former director of the museum. The species, on the other hand, was named after a local municipality called Cene
Cene
Cene is a comune in the Province of Bergamo in the Italian region of Lombardy, located about 60 km northeast of Milan and about 15 km northeast of Bergamo...
neighbouring the site where the fossil was excavated. The specimen was given to palaeontologist Rupert Wild to study at the Staatliches Museum of Stuttgart
Stuttgart
Stuttgart is the capital of the state of Baden-Württemberg in southern Germany. The sixth-largest city in Germany, Stuttgart has a population of 600,038 while the metropolitan area has a population of 5.3 million ....
, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
. Wild named the genus and the type species in 1991
1991 in paleontology
-Birds:* Sankar Chatterjee's discovery of a possible Triassic bird, Protoavis, if genuine, would push avian origins back almost 70 million years. The find ignites controversy over the connection between dinosaurs and birds....
, but without describing it formally or providing the holotype specimen. Pinna (1993) provided the holotype and described it but the name "Vallesaurus" was considered a nomen nudum
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
. Renesto and Binelli named formally the genus and the type species in 2006
2006 in paleontology
-Insects:-Tetrapodomorphs:-Newly named temnospondylians:-Newly named amphibians:-Ichthyosaurs:-Newly named basal lepidosauromorphs:-Newly named plesiosaurs:-Newly named squamates:-Newly named crurotarsans:-Newly named dinosaurs:...
.
The second species, V. zorzinensis, was found in the same location and identified from the specimen MCSNB 4783. The specific name referred to the Zorzino Limestone Formation, where the holotype was found.
Physical Charcteristics
Vallesaurus is a small drepanosaurid about 15 centimetres (5.9 in) long. It is pentadactyl, with the 4th digit being longest and equal in length to the humerusHumerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. Its tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
has a centrale
Carpus and tarsus of land vertebrates
The carpus and tarsus of land vertebrates primitively had three rows of carpal or tarsal bones. Often some of these have become lost or fused in evolution....
, or an ankle bone which articulates with the tibia
Tibia
The tibia , shinbone, or shankbone is the larger and stronger of the two bones in the leg below the knee in vertebrates , and connects the knee with the ankle bones....
. In addition, Vallesaurus also has modified distal tarsals
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
and metatarsals, and a clawless hallux
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
.
Vallesaurus differs in some characteristics from another drepanosaur, Megalancosaurus
Megalancosaurus
Megalancosaurus is a genus of extinct reptile from the Late Triassic period of Northern Italy, and one of the best known drepanosaurids. The type species is M. preonensis; a translation of the animal's scientific name would be "long armed reptile from the Preone Valley."-Anatomy:Megalancosaurus was...
. Vallesaurus has a proportionally shorter and higher snout, a thicker and larger maxilla
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...
and set of maxillary teeth, and a shorter cervical vertebra. It also lacks the fusion between the neural spines of the second and third dorsal vertebrae. Vallesaurus differs from Drepanosaurus
Drepanosaurus
Drepanosaurus is a genus of arboreal reptile that lived during the Triassic Period. Only one specimen of Drepanosaurus has thus far been found. Sadly this specimen was incomplete and lacked a head and neck...
, another drepanosaur, in that it lacks the enormous claw found on the second digit of the manus
Manus (zoology)
The manus is the zoological term for the distal portion of the fore limb of an animal. In tetrapods, it is the part of the pentadactyl limb that includes the metacarpals and digits . During evolution, it has taken many forms and served a variety of functions...
. It can be distinguished from Drepanosaurus, Megalancosaurus and possibly Dolabrosaurus
Dolabrosaurus
Dolabrosaurus is a genus of extinct reptile and a member of the family Drepanosauridae....
in the lack of a terminal spine at the end of the tail. In addition, Vallesaurus also differs from Hypuronector, a related drepanosaur, in having anteroposteriorly extended neural spines of the anterior dorsal vertebrae and forelimbs much shorter than the hindlimbs.
Behavioral Adaptations
Vallesaurus shares with all other known drepanosaurids a body structure that indicates a specialized adaptation toward climbing, especially on narrow supports such as the twigs of trees. The manus of Vallesaurus has no opposable fingers; however, the shape and length of the fingers suggest good climbing abilities.Vallesaurus as well as other drepanosaurids possess a fussed-like structure in the anterior dorsal region and highly modified cervical vertebrae with adaptations that limited lateral mobility. Both structures indicate the presence of powerful muscles and ligaments for the extension of the neck. This possibly suggests a projectile feeding adaptation. The head was suddenly launched forward to catch prey and the limited lateral mobility prevented undesired jerks of the neck which could have dislocated the cervical vertebrae during the quick extension. In smaller drepanosaurids like Megalancosaurus and Vallesaurus, such adaptations may be related to an insectivorous diet. The teeth of Vallesaurus seem well suited to cut or crush the tough exoskeleton
Exoskeleton
An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...
of insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and other arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s.