Loricata
Encyclopedia
Loricata is a group of reptiles that includes crocodylians and their ancestors. It was named by German
naturalist Blasius Merrem
in his 1820 Versuch eines Systems der Amphibien. Merrem considered it to be one of three groups of Pholidota (reptiles), the other two being Testudinata (turtle
s) and Squamata
(lizard
s and snake
s). Loricata was an early name for an order that includes crocodile
s, alligator
s, and gharial
s, although the order is now referred to as Crocodylia.
The name Loricata gained a new phylogenetic definition in 2011. In his study of early archosaur phylogeny, paleontologist Sterling J. Nesbitt defined it as the most inclusive clade containing Crocodylus niloticus (the Nile crocodile), but not the extinct Poposaurus gracilis
, Ornithosuchus longidens
, or Aetosaurus ferox
. Nesbitt considered the following features to be synapomorphies (distinguishing features) of Loricata:
Nesbitt's phylogenetic analysis placed Crocodylomorpha
and several rauisuchia
ns within Loricata. Rauisuchidae
was found to be the sister taxon of Crocodylomorpha, while prestosuchids formed a series of more basa
loricatans. Loricata is the sister taxon of Poposauroidea
, a group of Triassic rauisuchians. Below is a cladogram
of Loricata from Nesbitt (2011):
Poposauroids have often been viewed as closer relatives of crocodylomorphs than rauisuchids and prestosuchids are. The clade Paracrocodylomorpha
includes poposauroids and crocodylomorphs, usually excluding rauisuchids and prestosuchids. When Paracrocodylomorpha is used, rauisuchids and prestosuchids are usually placed as more basal crurotarsans. A clade called Paracrocodyliformes was erected in 2007 in which rauisuchids and prestosuchids were more closely related to Crocodylomorpha, and poposauroids were the most basal group. This usage is similar to Loricata.
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...
naturalist Blasius Merrem
Blasius Merrem
Blasius Merrem was a German naturalist.Merrem was born at Bremen, and studied at the university of Göttingen under Johann Friedrich Blumenbach. He developed an interest in zoology, particularly ornithology...
in his 1820 Versuch eines Systems der Amphibien. Merrem considered it to be one of three groups of Pholidota (reptiles), the other two being Testudinata (turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s) and Squamata
Squamata
Squamata, or the scaled reptiles, is the largest recent order of reptiles, including lizards and snakes. Members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the...
(lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s and snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s). Loricata was an early name for an order that includes crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...
s, alligator
Alligator
An alligator is a crocodilian in the genus Alligator of the family Alligatoridae. There are two extant alligator species: the American alligator and the Chinese alligator ....
s, and gharial
Gharial
The gharial , , also called Indian gavial or gavial, is the only surviving member of the once well-represented family Gavialidae, a long-established group of crocodilians with long, slender snouts...
s, although the order is now referred to as Crocodylia.
The name Loricata gained a new phylogenetic definition in 2011. In his study of early archosaur phylogeny, paleontologist Sterling J. Nesbitt defined it as the most inclusive clade containing Crocodylus niloticus (the Nile crocodile), but not the extinct Poposaurus gracilis
Poposaurus
Poposaurus is a genus of reptile from the Late Triassic of the southwestern United States. It was a crurotarsan archosaur which lived in what is now Wyoming, Utah, Arizona and Texas. The type species, Poposaurus gracilis, was described by M. G. Mehl in 1915. The second species, P...
, Ornithosuchus longidens
Ornithosuchus
Ornithosuchus is an extinct genus of crurotarsan from the Late Triassic Lossiemouth Sandstone of Scotland...
, or Aetosaurus ferox
Aetosaurus
Aetosaurus is an extinct genus of archosaur reptile belonging to the order Aetosauria. It is generally considered to be the most primitive aetosaur. Three species are currently recognized: A. ferratus, the type species from Germany and Italy; A. crassicauda from Germany; and A. arcuatus from...
. Nesbitt considered the following features to be synapomorphies (distinguishing features) of Loricata:
- Four teeth in the premaxillaPremaxillaThe 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....
of the upper jaw. - A ridge on the squamosalSquamosalThe squamosal is a bone of the head of higher vertebrates. It is the principal component of the cheek region in the skull, lying below the temporal series and otic notch and bounded anteriorly by postorbital. Posteriorly, the squamosal articulates with the posterior elements of the palatal complex,...
bone at the back of the skull. - A projection on the squamosal that touches the infratemporal fenestraInfratemporal fenestraAn infratemporal fenestra, also called the lateral temporal fenestra is an opening in the skull behind the orbit in some animals. An opening in front of the eye sockets, conversely, is called an antorbital fenestra. Both of these openings reduced the weight of the skull. Infratemporal fenestrae are...
. - A tall, narrow eye socketOrbit (anatomy)In anatomy, the orbit is the cavity or socket of the skull in which the eye and its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents...
. - A ridge positioned halfway along the length of the fibula for the attachment of the M. iliofibularis muscle.
- An articulation between the fourth tarsalTarsalTarsal could refer to:*tarsus *tarsus *superior tarsal muscle...
bone and the bottom of the calcaneum in the ankle. - A projection at the base of the fifth metatarsal of the foot that is separated from the end of the bone by a concave gap.
Nesbitt's phylogenetic analysis placed Crocodylomorpha
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
and several rauisuchia
Rauisuchia
Rauisuchia is a group of predatory and mostly large Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph...
ns within Loricata. Rauisuchidae
Rauisuchidae
Rauisuchidae is a group of large predatory Triassic archosaurs, and constitute advanced representatives of the larger group Rauisuchia. There is some disagreement over which genera should be included in the Prestosuchidae, which in Rauisuchidae, and which in the Poposauridae, and indeed whether...
was found to be the sister taxon of Crocodylomorpha, while prestosuchids formed a series of more basa
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:...
loricatans. Loricata is the sister taxon of Poposauroidea
Poposauroidea
Poposauroidea is a clade of rauisuchians. It includes poposaurids, shuvosaurids, and ctenosauriscids, but excludes the large predatory quadrupedal rauisuchians such as rauisuchids and prestosuchids. Although it was first formally defined in 2007, the term has been used for many years...
, a group of Triassic rauisuchians. Below is a cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
of Loricata from Nesbitt (2011):
Poposauroids have often been viewed as closer relatives of crocodylomorphs than rauisuchids and prestosuchids are. The clade Paracrocodylomorpha
Paracrocodylomorpha
Paracrocodylomorpha is a clade of crurotarsan archosaurs that includes crocodylomorphs and several closely related Triassic forms. Erected in 1993, the clade usually contains early crurotarsan taxa like Poposauridae and Gracilisuchus. These groups are considered sister taxa of the clade Bathyotica,...
includes poposauroids and crocodylomorphs, usually excluding rauisuchids and prestosuchids. When Paracrocodylomorpha is used, rauisuchids and prestosuchids are usually placed as more basal crurotarsans. A clade called Paracrocodyliformes was erected in 2007 in which rauisuchids and prestosuchids were more closely related to Crocodylomorpha, and poposauroids were the most basal group. This usage is similar to Loricata.