Kunbarrasaurus Temporal range: Early Cretaceous | |
---|---|
Holotype skeleton | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Thyreophora |
Clade: | † Ankylosauria |
Clade: | † Parankylosauria |
Genus: | † Kunbarrasaurus Leahey et al., 2015 |
Species: | †K. ieversi |
Binomial name | |
†Kunbarrasaurus ieversi Leahey et al., 2015 | |
Kunbarrasaurus (meaning "shield lizard") is an extinct genus of small ankylosaurian dinosaur from the Cretaceous of Australia. The genus conatins a single species, K. ieversi.
In November 1989, at Marathon Station near Richmond, Queensland, the skeleton was discovered of an ankylosaurian. In January 1990 it was secured by a team led by Ralph Molnar. In 1996, in a provisional description, Molnar concluded that it could be referred to the genus Minmi as a Minmi sp. [1] Subsequently, the specimen was further prepared by an acid bath and investigated by a CAT scan. The new information led to the conclusion that the species could be named in a separate genus of ankylosaur. [2]
In 2015, Lucy G. Leahey, Ralph E. Molnar, Kenneth Carpenter, Lawrence M. Witmer and Steven W. Salisbury named and described the type species Kunbarrasaurus ieversi. The genus name is derived from Kunbarra - the word for 'shield' in the Mayi language of the local Wunumara people. The specific name ieversi honours Mr Ian Ivers, the property manager who originally found the fossil. The description was limited to the skull. [2] Kunbarrasaurus was one of eighteen dinosaur taxa from 2015 to be described in open access or free-to-read journals. [3]
The holotype, QM F1801, was found in a layer of the Allaru Formation, marine sediments dating from the late Albian, or possibly the early Cenomanian. It consists of an almost complete skeleton with skull, containing the vertebral column up to the middle tail, the left shoulder girdle, the left arm minus the hand, the pelvis, both thighbones and most of the body armour. Both the bones and the armour are largely articulated. In the belly region remains have been found of the animal's last meal. The specimen represents the most complete dinosaur skeleton ever found in Eastern Gondwana (Australia, Antarctica, Madagascar and India) and the most complete ankylosaurian skeleton from the entirety of the Gondwanan continents. [2]
Five specimens earlier referred to a Minmi sp. were not referred to Kunbarrasaurus by the 2015 description.[ citation needed ]
In 2022, a specimen collected in 2005 by Benjamin P. Kear from Warra Station near Boulia, Queensland, SAMA P40536 was described and referred to Kunbarrasaurus. However, the describing authors refrained from referring it to K. leversi because it did not share any unique features with the type specimen. It was found in a layer belonging to the Toolebuc Formation, which directly underlies the Allaru Mudstone and dates to the middle-upper Albian. The specimen consists of a partial skull associated with elements from the postcrania. Unfortunately, most of the postcranial skeleton remains in limestone and therefore not ready for description. [4]
Kunbarrasaurus was a small quadrupedal armoured dinosaur. Its length has been estimated at 2.5–3.5 metres (8.2–11.5 ft). [1] [5]
In 2015, some distinguishing traits of the skull of Kunbarrasaurus were established. The roof of the skull is almost perfectly flat, apart from a limited convex profile of the postorbital bone and the nasal bone. The edges of the skull top, formed by the prefrontal, supraorbital and postorbital bones, make a right angle with the skull sides. The supraorbital is made up of one bone instead of two or three. The prefrontal is only exposed on the skull roof and does not reach the eye socket. The nasal bone does not reach the snout side and is limited to the snout top and the large, more centrally placed, opening around the nostril. This opening, which is completely located in the nasal bone, is large compared to the maxillary part of the snout and fully accessible from above and the side. The maxilla vertically attains the full height of the skull, reaching to the prefrontal on the skull roof. The hindmost tooth is positioned under the rear edge of the eye socket. [2]
The lacrimal bone is directed vertically. The pterygoid bones do not touch each other with their rear ends at the braincase, totally separated by the basisphenoid. The quadrate is vertically oriented. The coronoid process of the lower jaw is strongly protruding. The side of the braincase largely consists of cartilage instead of bone, so that many brain nerves must have had their exits in a single large opening, rather than separate small ones. The inner ear is very large compared with the skull as a whole and differs from that of all other known Dinosauria in the ear vestibule not being separated from the brain cavity, the floor for the cochlea not being made of bone and the vestibule being so large that the semicircular canals are shortened. The skull osteoderms are flat or at most have a low keel. There are no squamosal or quadratojugal horns or bosses on the upper skull corners or the cheeks. [2]
Kunbarrasaurus had bony protrusions, also known as body armour, in the skin on its head, back, abdomen, legs and along the tail. Several types of armour are known in place in Kunbarrasaurus, including small ossicles, small keeled scutes on the body ordered in parallel longitudinal rows, large scutes without keels on the snout, large keeled scutes on the neck, shoulders, and possibly tail, spike-like scutes on the hips, and a combination of ridged and keeled scutes and triangular plates on the tail. There was one preserved ring of scutes around the neck. A sacral shield is absent. [6]
The exact arrangement of armour on the tail is unclear, although it appears that there were triangular plates that ran on the sides of the tail, with long scutes forming a row along the top of the tail. [6] While most of the tail is not preserved, some of the relatives of Kunbarrasaurus, including Stegouros and Antarctopelta , had a large macuahuitl-like structure at the end of the tail, formed by expanded triangular flattened osteoderms. [5] [7]
Kunbarrasaurus was in 2015 placed in the Ankylosauria. The same year Victoria Arbour e.a. had entered QM F1801 and the Minmi holotype as separate operational taxonomic units in their analysis. Whereas Minmi was recovered as a basal member of the Ankylosauridae, QM F1801 had a basal position in Ankylosauria, i.e. was too "primitive" to be included in either the Ankylosauridae or Nodosauridae. [8] In the 2015 description of Kunbarrasaurus on qualitative considerations such a position was indeed deemed likely. [2]
In 2021, Sergio Soto-Acuña et al. found Kunbarrasaurus to belong to a distinctive basal lineage of Southern Hemisphere ankylosaurs, the Parankylosauria. Their phylogenetic analyses placed it as the sister taxon to the clade formed by the Late Cretaceous Stegouros and Antarctopelta. [5]
As with other ankylosaurians, Kunbarrasaurus was herbivorous. Unlike most herbivorous dinosaurs, there is direct evidence of the diet of Kunbarrasaurus: gut contents are known from the well-preserved nearly complete holotype specimen, found in the abdominal cavity in front of the left ilium.
The gut contents consist of fragments of fibrous or vascular plant tissue, fruiting bodies, spherical seeds, and vesicular tissue (possibly from fern sporangia). The most common remains are the fibrous or vascular fragments, which are typically rather uniform in size at 0.6 to 2.7 millimetres (0.024 to 0.106 inches) long and have clean cuts at their ends, perpendicular to a given fragment's long axis. Because of the small size of the fragments, they have been interpreted as having been nibbled from plants or chopped in the mouth, evidence of some method of retaining food in the mouth. These small fragments may have come from twigs or stems, but their size is more suggestive of vascular bundles in leaves. The clean cuts and lack of gastroliths suggest that the animal relied on oral processing instead of gastroliths or grit to grind food. The seeds (0.3 mm [0.01 in] across) and fruiting bodies (4.5 mm [0.18 in] across) were apparently swallowed whole. Comparisons with gut contents and scat from other modern herbivores like lizards, emus, and geese indicate that this Kunbarrasaurus individual had a more sophisticated process for cutting up plant material. [9]
Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are known to have first appeared in the Middle Jurassic, and persisted until the end of the Cretaceous Period. The two main families of Ankylosaurs, Nodosauridae and Ankylosauridae are primarily known from the Northern Hemisphere, but the more basal Parankylosauria are known from southern Gondwana during the Cretaceous.
Ankylosaurus is a genus of armored dinosaur. Its fossils have been found in geological formations dating to the very end of the Cretaceous Period, about 68–66 million years ago, in western North America, making it among the last of the non-avian dinosaurs. It was named by Barnum Brown in 1908; it is monotypic, containing only A. magniventris. The generic name means "fused" or "bent lizard", and the specific name means "great belly". A handful of specimens have been excavated to date, but a complete skeleton has not been discovered. Though other members of Ankylosauria are represented by more extensive fossil material, Ankylosaurus is often considered the archetypal member of its group, despite having some unusual features.
Muttaburrasaurus was a genus of herbivorous iguanodontian ornithopod dinosaur, which lived in what is now northeastern Australia sometime between 112 and 103 million years ago during the early Cretaceous period. It has been recovered in some analyses as a member of the iguanodontian clade Rhabdodontomorpha. After Kunbarrasaurus, it is Australia's most completely known dinosaur from skeletal remains. It was named after Muttaburra, the site in Queensland, Australia, where it was found.
Euoplocephalus is a genus of large herbivorous ankylosaurid dinosaurs, living during the Late Cretaceous of Canada. It has only one named species, Euoplocephalus tutus.
Polacanthus, deriving its name from the Ancient Greek polys-/πολύς- "many" and akantha/ἄκανθα "thorn" or "prickle", is an early armoured, spiked, plant-eating ankylosaurian dinosaur from the early Cretaceous period of England.
Scelidosaurus is a genus of herbivorous armoured ornithischian dinosaur from the Jurassic of England.
Minmi is a genus of small herbivorous ankylosaurian dinosaur that lived during the early Cretaceous Period of Australia, about 120 to 112 million years ago.
Edmontonia is a genus of panoplosaurin nodosaurid dinosaur from the Late Cretaceous Period. It is part of the Nodosauridae, a family within Ankylosauria. It is named after the Edmonton Formation, the unit of rock where it was found.
Pinacosaurus is a genus of ankylosaurid thyreophoran dinosaur that lived in Asia during the Late Cretaceous, mainly in Mongolia and China.
Gastonia is a genus of herbivorous ankylosaurian dinosaur from the Early Cretaceous of North America, around 139 to 134.6 million years ago. It is often considered a nodosaurid closely related to Polacanthus. Gastonia has a sacral shield and large shoulder spikes.
Ankylosauridae is a family of armored dinosaurs within Ankylosauria, and is the sister group to Nodosauridae. The oldest known Ankylosaurids date to around 122 million years ago and went extinct 66 million years ago during the Cretaceous–Paleogene extinction event. These animals were mainly herbivorous and were obligate quadrupeds, with leaf-shaped teeth and robust, scute-covered bodies. Ankylosaurids possess a distinctly domed and short snout, wedge-shaped osteoderms on their skull, scutes along their torso, and a tail club.
Aletopelta is a monospecific genus of basal ankylosaurid dinosaur from Southern California that lived during the Late Cretaceous in what is now the Point Loma Formation. The type and only species, Aletopelta coombsi, is known from a partial skeleton preserving osteoderms. It was originally described in 1996 by W. P. Coombs, Jr. and T.A. Deméré before being named in 2001 by Tracy Ford and James Kirkland. Aletopelta has an estimated size of 5 metres and weight of 2 tonnes. The holotype formed a miniature reef and was scavenged upon by invertebrates and sharks.
Sauropelta is a genus of nodosaurid dinosaur that existed in the Early Cretaceous Period of North America. One species has been named although others may have existed. Anatomically, Sauropelta is one of the most well-understood nodosaurids, with fossilized remains recovered in the U.S. states of Wyoming, Montana, and possibly Utah. It is also the earliest known genus of nodosaurinae; most of its remains are found in a section of the Cloverly Formation dated to 108.5 million years ago.
Shamosaurus is an extinct genus of herbivorous basal ankylosaurid ankylosaur from Early Cretaceous deposits of Höövör, Mongolia.
Cedarpelta is an extinct genus of basal ankylosaurid dinosaur from Utah that lived during the Late Cretaceous period in what is now the Mussentuchit Member of the Cedar Mountain Formation. The type and only species, Cedarpelta bilbeyhallorum, is known from multiple specimens including partial skulls and postcranial material. It was named in 2001 by Kenneth Carpenter, James Kirkland, Don Burge, and John Bird. Cedarpelta has an estimated length of 7 metres and weight of 5 tonnes (11,023 lbs). The skull of Cedarpelta lacks extensive cranial ornamentation and is one of the only known ankylosaurs with individual skull bones that are not completely fused together.
Antarctopelta is a genus of ankylosaurian dinosaur, a group of large, quadrupedal herbivores, that lived during the Maastrichtian stage of the Late Cretaceous period on what is now James Ross Island, Antarctica. Antarctopelta is the only known ankylosaur from Antarctica and a member of Parankylosauria. The only described specimen was found in 1986, the first dinosaur to be found on the continent, by Argentine geologists Eduardo Olivero and Robert Scasso. The fossils were later described in 2006 by paleontologists Leonardo Salgado and Zulma Gasparini, who named the type species A. oliveroi after Olivero.
Europelta is a monospecific genus of nodosaurid dinosaur from Spain that lived during the Early Cretaceous in what is now the lower Escucha Formation of the Teruel Province. The type and only species, Europelta carbonensis, is known from two associated partial skeletons, and represents the most complete ankylosaur known from Europe. Europelta was named in 2013 by James I. Kirkland and colleagues. Europelta has an estimated length of 5 metres and weight of 1.3 tonnes, making it the largest member of the clade Struthiosaurini.
This timeline of ankylosaur research is a chronological listing of events in the history of paleontology focused on the ankylosaurs, quadrupedal herbivorous dinosaurs who were protected by a covering bony plates and spikes and sometimes by a clubbed tail. Although formally trained scientists did not begin documenting ankylosaur fossils until the early 19th century, Native Americans had a long history of contact with these remains, which were generally interpreted through a mythological lens. The Delaware people have stories about smoking the bones of ancient monsters in a magic ritual to have wishes granted and ankylosaur fossils are among the local fossils that may have been used like this. The Native Americans of the modern southwestern United States tell stories about an armored monster named Yeitso that may have been influenced by local ankylosaur fossils. Likewise, ankylosaur remains are among the dinosaur bones found along the Red Deer River of Alberta, Canada where the Piegan people believe that the Grandfather of the Buffalo once lived.
Stegouros is a genus of ankylosaurian dinosaur from the Late Cretaceous Dorotea Formation of southern Chile. The genus contains a single species, Stegouros elengassen, known from a semi-articulated, near-complete skeleton.
Parankylosauria is a group of basal ankylosaurian dinosaurs known from the Cretaceous of South America, Antarctica, and Australia. It is thought the group split from other ankylosaurs during the mid-Jurassic period, despite this being unpreserved in the fossil record.