Proximodorsal process
Encyclopedia
The proximodorsal process
is a feature of the skeleton of archosaur
s. It may be a pair of tabs or blade - shaped flanges on the pelvis, and serves as an anchor point for the attachment of leg muscles. This process is of particular importance in the anatomy
and comparative morphology of Mesozoic
birds and advanced maniraptora
n dinosaur
s. The pelvis
is made up of three paired bones and a sacrum
. The three paired bones are called the ilium
, the ischium, and the pubis
. On the ischium there may be an obturator process
and/or a proximodorsal process. The more primitive condition is for there to be no proximodorsal process, but a large obturator process
. In primitive birds the ischia are complex, usually with a small or even absent obturator process and a large, rectangular, proximodorsal process extending up toward the ilium. This is the condition in Archaeopteryx
, Confuciusornis
, and enantiornithines. The South American dromaeosaurs called the unenlagiinae
have an intermediate condition between the two, with both a large obturator process and a proximodorsal process.
Process (anatomy)
In anatomy, a process is a projection or outgrowth of tissue from a larger body. The vertebra has several kinds of processes,such as: transverse process, prezygapophysis, postzygapophysis.-Examples:Examples of processes include:...
is a feature of the skeleton of archosaur
Archosaur
Archosaurs are a group of diapsid amniotes whose living representatives consist of modern birds and crocodilians. This group also includes all extinct non-avian dinosaurs, many extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most...
s. It may be a pair of tabs or blade - shaped flanges on the pelvis, and serves as an anchor point for the attachment of leg muscles. This process is of particular importance in the anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
and comparative morphology of Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
birds and advanced maniraptora
Maniraptora
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the dinosaurs that were more closely related to them than to Ornithomimus velox. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. Ornitholestes and the Alvarezsauroidea...
n 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...
s. The pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
is made up of three paired bones and a sacrum
Sacrum
In vertebrate anatomy the sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part connects with the last lumbar vertebra, and bottom part with the coccyx...
. The three paired bones are called the ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
, the ischium, and the pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
. On the ischium there may be an obturator process
Obturator process
The obturator process is an anatomical feature on the pelvis of archosaurs. It is a raised area of the ischium bone of the pelvis. It is the origin of muscles that attach to the femur and aid in running. These muscles are called M. pubo-ischio-femoralis externus 1 and 2 in crocodylians. In birds...
and/or a proximodorsal process. The more primitive condition is for there to be no proximodorsal process, but a large obturator process
Obturator process
The obturator process is an anatomical feature on the pelvis of archosaurs. It is a raised area of the ischium bone of the pelvis. It is the origin of muscles that attach to the femur and aid in running. These muscles are called M. pubo-ischio-femoralis externus 1 and 2 in crocodylians. In birds...
. In primitive birds the ischia are complex, usually with a small or even absent obturator process and a large, rectangular, proximodorsal process extending up toward the ilium. This is the condition in Archaeopteryx
Archaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
, Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...
, and enantiornithines. The South American dromaeosaurs called the unenlagiinae
Unenlagiinae
Unenlagiinae is a subfamily of Dromaeosauridae. Unenlagiines are one of the most basal lineages of dromaeosaurids. Unenlagiines are known from South America and Madagascar....
have an intermediate condition between the two, with both a large obturator process and a proximodorsal process.