Ankylosauridae
Encyclopedia
An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs
that evolved 125 million years ago (along with another family of ankylosaurs
, the Nodosauridae
) and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event
. Ankylosaurids have been found in western North America
, Europe
and East Asia
, though good specimens are rare; most are known only from bone fragments.
, forming a veritable shell on the backs of ankylosaurids and their clubbed
tails, makes them look superficially similar to the mammalian glyptodonts
(and to a lesser degree to the giant meiolaniid
turtles of Australia
).
Their heavily armoured heads formed a toothless beak at the front (comparable to modern birds), though the sides of the mouth and the lower jaw did bear small teeth, deeply inset from the jaw.
has traditionally been used to separate ankylosaurids from their close relatives the nodosaurids, although the many primitive ankylosaurids ("shamosaurines", and even basal ankylosaurines) also lacked tail clubs.
are sometimes included as a subfamily of ankylosaurids, as Polacanthinae. However, phylogenetic analyses since 2000 have shown the polacanthids to form either a natural group apart from the ankylosaurids, or to be an unnatural grouping of primitive ankylosaurs.
The following uses the ranks from Benton 2004. The following taxonomy follows Thompson et al., 2011 unless otherwise noted.
". Sereno, 2005 redefined it as: The most inclusive clade containing Ankylosaurus magniventris but not Panoplosaurus
mirus. Ankylosaurinae was first named by Nopcsa
in 1918 and defined by Sereno, 1998 as "all ankylosaurids more closely related to Ankylosaurus than to Shamosaurus
". Sereno, 2005 redefined it as: The most inclusive clade containing Ankylosaurus magniventris but not Gargoyleosaurus parkpinorum, Minmi
paravertebra, or Shamosaurus scutatus. The cladogram
below follows the most resolved topology from a 2011 analysis by paleontologists Richard S. Thompson, Jolyon C. Parish, Susannah C. R. Maidment and Paul M. Barrett.
Thyreophora
The Thyreophora were a subgroup of the ornithischian dinosaurs...
that evolved 125 million years ago (along with another family of ankylosaurs
Ankylosauria
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are first known to have appeared in the early Jurassic Period of...
, the Nodosauridae
Nodosauridae
Nodosauridae is a family of ankylosaurian dinosaurs, from the Late Jurassic to the Late Cretaceous Period of what are now North America, Asia, Antarctica and Europe.-Characteristics:...
) and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event
Cretaceous-Tertiary extinction event
The Cretaceous–Paleogene extinction event, formerly named and still commonly referred to as the Cretaceous-Tertiary extinction event, occurred approximately 65.5 million years ago at the end of the Maastrichtian age of the Cretaceous period. It was a large-scale mass extinction of animal and plant...
. Ankylosaurids have been found in western 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...
, Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
and East Asia
East Asia
East Asia or Eastern Asia is a subregion of Asia that can be defined in either geographical or cultural terms...
, though good specimens are rare; most are known only from bone fragments.
Features
The heavy armourArmour (zoology)
Armour in animals is external or superficial protection against attack by predators, formed as part of the body , usually through the hardening of body tissues, outgrowths or secretions. It has therefore mostly developed in 'prey' species...
, forming a veritable shell on the backs of ankylosaurids and their clubbed
Club (zoology)
In zoology, a club is a bony mass at the end of the tail of some dinosaurs and of some mammals, most notably the ankylosaurids and the glyptodonts...
tails, makes them look superficially similar to the mammalian glyptodonts
Glyptodontidae
Glyptodonts were large, more heavily armored relatives of extinct pampatheres and modern armadillos.They first evolved during the Miocene in South America, which remained their center of species diversity...
(and to a lesser degree to the giant meiolaniid
Meiolania
Meiolania is an extinct genus of cryptodire turtle from the Oligocene to Holocene, with the last relict populations at New Caledonia which survived until 2,000 years ago....
turtles of Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
).
Their heavily armoured heads formed a toothless beak at the front (comparable to modern birds), though the sides of the mouth and the lower jaw did bear small teeth, deeply inset from the jaw.
Armor
Ankylosaurids usually had a thick armour plating of fused bone, often interspersed with a variety of spikes and lumps. Ankylosaurids were so heavily armored that some advanced species even had armoured eyelids.Tail
Many ankylosaurids also had an enlarged mass of bone forming a "club" on the end of their tails, made of two enlarged bone lumps. This tail clubClub (zoology)
In zoology, a club is a bony mass at the end of the tail of some dinosaurs and of some mammals, most notably the ankylosaurids and the glyptodonts...
has traditionally been used to separate ankylosaurids from their close relatives the nodosaurids, although the many primitive ankylosaurids ("shamosaurines", and even basal ankylosaurines) also lacked tail clubs.
Taxonomy
The polacanthidsPolacanthidae
Polacanthidae is a group of ankylosaurs. Polacanthids are late Jurassic to early Cretaceous in age, and Kirkland observed they appeared to become extinct about the same time a land bridge opened between Asia and North America....
are sometimes included as a subfamily of ankylosaurids, as Polacanthinae. However, phylogenetic analyses since 2000 have shown the polacanthids to form either a natural group apart from the ankylosaurids, or to be an unnatural grouping of primitive ankylosaurs.
The following uses the ranks from Benton 2004. The following taxonomy follows Thompson et al., 2011 unless otherwise noted.
- Family Ankylosauridae
- AletopeltaAletopeltaAletopelta coombsi was an ankylosaurian ornithischian dinosaur whose fossils were found in Southern California.Etymologically, the generic name is composed of the Greek terms aletes and pelte, meaning, respectively "wandering" and "shield"...
- CedarpeltaCedarpeltaCedarpelta is an extinct genus of basal ankylosaurid ankylosaur, based on material recovered from the Lower Cretaceous of North America. The skull lacks extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for ankylosaurs....
- GobisaurusGobisaurusGobisaurus is an extinct genus of basal ankylosaurid ankylosaur from the Upper Cretaceous Ulansuhai Formation of China. The holotype consists of a skull and as yet undescribed postcranial remains. It was first named by Matthew K. Vickaryous, Anthony P. Russell, Philip J...
- LiaoningosaurusLiaoningosaurusLiaoningosaurus is a very unusual ankylosaur from the Lower Cretaceous. The holotype IVPP V12560 , an essentially complete juvenile skeleton compressed on a slab, was collected from the Yixian Formation of Liaoxi, Yixian County, Liaoning Province, People's Republic of China.The type species...
- MinmiMinmi (dinosaur)Minmi, named after Minmi Crossing, Australia , is a genus of small ankylosaurian dinosaur that lived during the early Cretaceous Period, about 119 to 113 million years ago. The type species, M. paravertebra, was described by Ralph Molnar in 1980...
- ShamosaurusShamosaurusShamosaurus is an extinct genus of basal ankylosaurid ankylosaur from Early Cretaceous deposits of Höövör, Mongolia. Shamosaurus is known from the holotype PIN N 3779/2 complete skull and jaw and the paratypes include partial skeleton remains and an armor. It was collected from the...
- Subfamily Ankylosaurinae
- AhshislepeltaAhshislepeltaAhshislepelta is a genus of herbivorousankylosaurine ankylosaurid dinosaur from Late Cretaceous deposits of San Juan Basin, New Mexico....
- AnkylosaurusAnkylosaurusAnkylosaurus is a genus of ankylosaurid dinosaur, containing one species, A. magniventris...
- CrichtonsaurusCrichtonsaurusCrichtonsaurus is a genus of ankylosaurid ankylosaur dinosaur named for Michael Crichton, the author of Jurassic Park. It was an ankylosaurine, and it lived during the late Cretaceous Period. Its fossils were discovered in China, and it was formally described by Dong Zhiming in 2002. The type...
- DyoplosaurusDyoplosaurusDyoplosaurus is the name given to a genus of ankylosaurid dinosaur. It lived during the Late Cretaceous near what is now the Red Deer River in Alberta, Canada and was named by William Parks in 1924, based on holotype ROM 784, a partial skeleton including parts of the skull and lower jaws.The type...
- EuoplocephalusEuoplocephalusEuoplocephalus was one of the largest genera of ankylosaurian dinosaurs, at about the size of a small elephant. It is also the ankylosaurian with the best fossil record, so its extensive spiked armor, low-slung body and great club-like tail are well documented.-Description:Among the...
- MinotaurasaurusMinotaurasaurusMinotaurasaurus is a genus of ankylosaurine ankylosaurid dinosaur that lived during the Late Cretaceous. It was named in 2009 by Clifford A. Miles and Clark J. Miles and the type species is Minotaurasaurus ramachandrani. The generic name is explained by the describers as meaning "man-bull reptile";...
- NodocephalosaurusNodocephalosaurusNodocephalosaurus is a genus of herbivorous ankylosaurine ankylosaurid dinosaur from Upper Cretaceous deposits of San Juan Basin, New Mexico. The holotype was recovered from the Late Campanian De-na-zin Member of the Kirtland Formation and consists of an incomplete skull...
- PinacosaurusPinacosaurusPinacosaurus is a genus of medium-sized ankylosaur dinosaurs that lived from the late Santonian to the late Campanian stages of the late Cretaceous Period , in Mongolia and China...
- SaichaniaSaichaniaSaichania is a genus of ankylosaurid dinosaur from the Late Cretaceous period. It was found in the Barun Goyot Formation at Khulsan in the Nemegt Basin, southern Mongolia. It lived during the Campanian. The type species is Saichania chulsanensis.Saichania was described by Teresa Maryańska in 1977,...
- ShanxiaShanxiaShanxia is a genus of ankylosaurid dinosaur that lived during the upper Cretaceous Period. Its fossils were recovered and named after the Shanxi Province of China, and it is known only from scrappy remains found in river deposits...
- TalarurusTalarurusTalarurus is a genus of hippopotamus-sized ankylosaurid dinosaur with heavy armour and a club tail. It was named by Evgeny Maleev in 1952.-Age and location:...
- TarchiaTarchiaTarchia is a genus of ankylosaurid dinosaur from the late Cretaceous of Mongolia. It is currently the geologically youngest known of all the Asian ankylosaurid dinosaurs and is represented by five or more specimens, including two complete skulls and one nearly complete postcranial skeleton...
- TianzhenosaurusTianzhenosaurusTianzhenosaurus is a genus of ankylosaurid dinosaur discovered in Tianzhen County, at Kangdailiang near Zhaojiagou Village, in Shanxi Province, China, in the Late Cretaceous Huiquanpu Formation. Thus far, a virtually complete skull and postcranial skeleton have been assigned to the genus, which is...
- TsagantegiaTsagantegiaTsagantegia is a genus of medium-sized ankylosaurid dinosaur from the Upper Cretaceous Mongolia, during the Cenomanian stage.The holotype specimen , a complete skull, was recovered from the Bayan Shireh Formation , at the Tsagan-Teg locality, Dzun-Bayan, in the southeastern Gobi Desert, Mongolia...
- ZhongyuansaurusZhongyuansaurusZhongyuansaurus is an extinct genus of ankylosaurid ankylosaurian dinosaur from the Cretaceous of Ruyang, Henan, China. It is known from remains including skull, arm, pelvic, and tail bones. It is distinguished by characteristics such as a flat roof to the skull, a straight ischium, and the...
- Ahshislepelta
- Aletopelta
Phylogeny
Ankylosauridae was first named by Brown in 1908 and defined by him as "all ankylosaurs more closely related to Ankylosaurus than to PanoplosaurusPanoplosaurus
Panoplosaurus is a genus of nodosaurid dinosaur. It was one of the last known nodosaurids, living during the Late Cretaceous in what is now North America; fossils have been located in Alberta, Canada....
". Sereno, 2005 redefined it as: The most inclusive clade containing Ankylosaurus magniventris but not Panoplosaurus
Panoplosaurus
Panoplosaurus is a genus of nodosaurid dinosaur. It was one of the last known nodosaurids, living during the Late Cretaceous in what is now North America; fossils have been located in Alberta, Canada....
mirus. Ankylosaurinae was first named by Nopcsa
Franz Nopcsa von Felso-Szilvás
Baron Franz Nopcsa von Felső-Szilvás was a Hungarian-born aristocrat, adventurer, scholar, and paleontologist...
in 1918 and defined by Sereno, 1998 as "all ankylosaurids more closely related to Ankylosaurus than to Shamosaurus
Shamosaurus
Shamosaurus is an extinct genus of basal ankylosaurid ankylosaur from Early Cretaceous deposits of Höövör, Mongolia. Shamosaurus is known from the holotype PIN N 3779/2 complete skull and jaw and the paratypes include partial skeleton remains and an armor. It was collected from the...
". Sereno, 2005 redefined it as: The most inclusive clade containing Ankylosaurus magniventris but not Gargoyleosaurus parkpinorum, Minmi
Minmi (dinosaur)
Minmi, named after Minmi Crossing, Australia , is a genus of small ankylosaurian dinosaur that lived during the early Cretaceous Period, about 119 to 113 million years ago. The type species, M. paravertebra, was described by Ralph Molnar in 1980...
paravertebra, or Shamosaurus scutatus. The 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...
below follows the most resolved topology from a 2011 analysis by paleontologists Richard S. Thompson, Jolyon C. Parish, Susannah C. R. Maidment and Paul M. Barrett.
External links
- Ankylosauridae
- Family Tree
- Ankylosauridae Tree of Life web project