Minmi Temporal range: Early Cretaceous ~ | |
---|---|
Left foot of the holotype | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Thyreophora |
Clade: | † Eurypoda |
Clade: | † Ankylosauria |
Genus: | † Minmi Molnar, 1980 |
Species: | †M. paravertebra |
Binomial name | |
†Minmi paravertebra Molnar, 1980 | |
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.
In 1964, Dr Alan Bartholomai, a collaborator of the Queensland Museum, discovered a chalkstone nodule containing an ankylosaurian skeleton in Queensland near Minmi Crossing, along the Injun Road, one kilometre south of Mack Gulley, north of Roma. [1]
In 1980, Ralph E. Molnar named and described the type species, in this case the only species known in the genus, Minmi paravertebra. The generic name, at the time the shortest of a Mesozoic dinosaur, refers to Minmi Crossing. The meaning of "minmi" itself is uncertain; it refers to a large lily in the local aboriginal language but might also be derived from min min , a kind of will-o'-the-wisp. The specific name refers to strange bone elements found along the vertebrae, for which Molnar coined the designation paravertebrae. [1]
The holotype, QM F10329, was discovered in a layer of the Bungil Formation, the Minmi Member, a lagoon deposit which was first dated to the Barremian-Valanginian, but later was recalibrated to the Aptian. It consists of a partial skeleton, lacking the skull. It preserves a series of eleven back vertebrae, ribs, a right hindlimb, and plates of the belly armour. [1] It was the first specimen of a thyreophoran discovered in the Southern Hemisphere.
In 1989, a much more complete skeleton was discovered, specimen QM F1801 that includes the skull and shows an articulated body armour. It was referred to a Minmi sp. Since 1989, most information provided on Minmi in books and illustrations is based on this second exemplar, but in 2015, it was named as a separate genus, Kunbarrasaurus . [2]
Between 1989 and 1996 several other specimens were discovered and ultimately referred to a Minmi sp. These include QM F33286: a rump with pelvis and osteoderms; AM F35259: ribs with osteoderms; QM F33565: a partial thighbone; and QM F33566: a partial shinbone, perhaps of the same individual as QM F33565. AM F35259 is part of the collection of the Australian Museum. [3] Later specimen QM F119849 was reported, consisting of ribs and osteoderms. [4]
Minmi was a small herbivorous quadrupedal armoured ankylosaurian. In 2016, Gregory S. Paul estimated its length at 3 metres (9.8 ft), its weight at 300 kilograms (660 lb). [5] For an ankylosaurian, Minmi had long limbs, perhaps used to quickly search cover under brushes when threatened by large predators which might have been able to flip the small animal on its back. [6]
Unlike other ankylosaurians, Minmi had horizontally oriented plates of bones that ran along the sides of its vertebrae, hence its specific name, paravertebra. Molnar in 1980 acknowledged that these were ossified tendons, but denied that they were homologous to the ossified tendons of other Ornithischia and claimed that they resembled the pathological tendon aponeurosis of modern crocodiles. Victoria Megan Arbour in 2014 deemed this unlikely and could find only one autapomorphy in the holotype: [7] the high vertical extent of the musculus articulospinalis tendon ossification at its outer front end, wrapping itself around the side process of the vertebra. In 2015, Arbour and Philip Currie concluded that even this was not unique, which would mean the holotype had no diagnostic features and Minmi would be a nomen dubium . [8] However, the 2015 description of Kunbarrasaurus announced that new distinguishing traits of Minmi had been discovered and that it should be considered a valid taxon. [2] In 2021, Rozadilla and colleagues argued that Minmi is indeed distinct from its relatives like Struthiosaurus and should be considered a valid taxon. [9]
In 1980, Molnar placed Minmi in the Ankylosauria. [1] In 1987, he thought it was a member of the Nodosauridae. [10] In 2011, a new cladistic analysis performed by Thompson et al. recovered Minmi as the basalmost known ankylosaurid. [11] Arbour & Currie entered Minmi and Minmi sp. as separate operational taxonomic units in their analysis and recovered Minmi as the basalmost ankylosaurid but Minmi sp. (= Kunbarrasaurus) as a more basal ankylosaurian, too "primitive" to be included in either the Ankylosauridae or Nodosauridae. [8]
A 2023 phylogenetic analysis recovered Minmi as an eurypodan outside Stegosauria and Ankylosauria due to the lack of ankylosaur synapomorphies. [12] A 2024 phylogenetic analysis recovered it as an ankylosaurian of uncertain taxonomic family. [13]
A scientific paper that was published in the year 2000 by Ralph E. Molnar and Harold Trevor Clifford found that Minmi was a low browser and grazer whose diet consisted of plants that grew low to the ground. Its diet consisted of plants such as seeds, fruit, flowering plants, and ferns. [14]
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 North Africa during the Middle Jurassic, and persisted until the end of the Late Cretaceous. The two main families of ankylosaurians, Nodosauridae and Ankylosauridae are primarily known from the Northern Hemisphere, but the more basal Parankylosauria are known from southern Gondwana during the Cretaceous.
Euoplocephalus is a genus of large herbivorous ankylosaurid dinosaurs, living during the Late Cretaceous of Canada. It has only one named species, Euoplocephalus tutus.
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.
Nodosauridae is a family of ankylosaurian dinosaurs known from the Late Jurassic to the Late Cretaceous periods in what is now Asia, Europe, North America, and possibly South America. While traditionally regarded as a monophyletic clade as the sister taxon to the Ankylosauridae, some analyses recover it as a paraphyletic grade leading to the ankylosaurids.
Dyoplosaurus is a monospecific genus of ankylosaurid dinosaur from Alberta that lived during the Late Cretaceous in what is now the Dinosaur Park Formation. Dyoplosaurus represents a close relative of Scolosaurus and Anodontosaurus, two ankylosaurids known from the Horseshoe Canyon and Dinosaur Park Formation.
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.
Tianzhenosaurus is a monospecific genus of ankylosaurid dinosaur from the Shanxi Province that lived during the Late Cretaceous in what is now the Huiquanpu Formation. Tianzhenosaurus may represent a junior synonym of Saichania, an ankylosaurine known from the Barun Goyot and Nemegt Formation.
Nodocephalosaurus is a monospecific genus of ankylosaurid dinosaur from New Mexico that lived during the Late Cretaceous in what is now the De-na-zin member of the Kirtland Formation. The type and only species, Nodocephalosaurus kirtlandensis, is known only from a partial skull. It was named in 1999 by Robert M. Sullivan. Nodocephalosaurus has an estimated length of 4.5 metres and weight of 1.5 tonnes. It is closely related and shares similar cranial anatomy to Akainacephalus.
Shanxia is a monospecific genus of ankylosaurid dinosaur from the Shanxi Province that lived during the Late Cretaceous in what is now the Huiquanpu Formation. Shanxia may possibly represent a junior synonym of Tianzhenosaurus, an ankylosaurine also known from the Huiquanpu Formation of China.
Polacanthinae is a subfamily of ankylosaurs, most often nodosaurids, from the Late Jurassic through Early Cretaceous of Europe and potentially North America and Asia. The group is defined as the largest clade closer to Polacanthus foxii than Nodosaurus textilis or Ankylosaurus magniventris, as long as that group nests within either Nodosauridae or Ankylosauridae. If Polacanthus, and by extent Polacanthinae, falls outside either family-level clade, then the -inae suffix would be inappropriate, and the proper name for the group would be the informally defined Polacanthidae.
Zhongyuansaurus is a monospecific genus of ankylosaurid dinosaur from Henan that lived during the Early Cretaceous in what is now the Haoling Formation. Zhongyuansaurus is possibly a junior synonym of Gobisaurus, a basal ankylosaurid from the Ulansuhai Formation of Inner Mongolia.
Zhejiangosaurus is an extinct genus of ankylosaurian dinosaur from the Upper Cretaceous of Zhejiang, eastern China. It was first named by a group of Chinese authors Lü Junchang, Jin Xingsheng, Sheng Yiming and Li Yihong in 2007 and the type species is Zhejiangosaurus lishuiensis. It has no diagnostic features, and thus is a nomen dubium.
Dongyangopelta is an monospecific genus of nodosaurid dinosaur that lived in China during the Early to Late Cretaceous period in what is now the Chaochuan Formation. The type and only known species, Dongyangopelta yangyanensis, is known from a partial postcranial skeleton preserving osteoderms and ossified tendons. It was named in 2013 by Rongjun Chen, Wenjie Zheng, Yoichi Azuma, Masateru Shibata, Tianling Lou, Qiang Jin and Xinsheng Jin. Dongyangopelta represents one of the only nodosaurids known from Asia, along with Taohelong and Sauroplites.
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.
Kunbarrasaurus is an extinct genus of small ankylosaurian dinosaur from the Cretaceous of Australia. The genus contains a single species, K. ieversi.
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.
Jakapil is a genus of basal thyreophoran dinosaur from the Candeleros Formation of Argentina. The type species is Jakapil kaniukura.
Patagopelta is an extinct genus of ankylosaurian dinosaur from the Late Cretaceous Allen Formation of Argentina. The genus contains a single species, P. cristata, known from a partial skeleton. While originally described as a nodosaurine, later discoveries provided support for parankylosaurian affinities for the taxon. Patagopelta is a very small ankylosaur, comparable in size to the dwarf nodosaurid Struthiosaurus, about 2 m (6.6 ft) long.