Cronopio
| Cronopio | ||||||||||||
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| 100 to 93 million years | ||||||||||||
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| Cronopio | ||||||||||||
| Rougier , Apesteguía & Gaetano , 2011 | ||||||||||||
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Cronopio dentiacutus is a mouse-sized mammal thatlivedin South America about 100 million years ago inthe Cretaceous period . The first discovery was made in Patagonia , Argentina . Cronopio belongs to the so-called dryolestoids , an already extinct group of animals from which today's marsupials and the higher mammals descend. Cronopio is named after the fictional characters from the collection of stories Historias de cronopios y de famas by the Argentine writer Julio Cortázar . The second part of the name dentiacutus is of Latin origin and refers to the pointed canine teeth (lat. Dens "tooth" and lat. Acutus "sharp, pointed").
features
Cronopio dentiacutus was approximately 10 to 12 cm long (excluding the tail). The skull of the holotype is about 27 mm long. It has a long, narrow snout, large eye sockets, specialized masticatory muscles and dagger-like canine teeth that are not found in any other mammal of the Mesozoic Era. Their length is 5 mm. Since there have not yet been any skull finds of this group, the Dryolestoids, the relationships could not be determined in more detail. Thanks to these first skull finds, however, it becomes clear that Cronopio still had numerous primitive properties. Its middle ear alone is similar in structure to that of today's mammals.
The first description by Cronopio includes three specimens: the holotype MPCA PV 454, an incomplete skull in which the cranial roof , the lower face (basicranium) and the scaly bone are missing, as well as the assigned specimens MPCA PV 450, an incomplete left lower jaw with damaged teeth, underneath posterior premolers and damaged molars , and MPCA PV 453, an incomplete skull with a relatively complete right mandible and missing incisors and canines . Since MPCA PV 454 and 453 complement each other well, Cronopio was able to reconstruct a skull in which only a few bones and teeth are missing: the lower incisors and canines, the septomaxilla - a bone in the anterior reptilian jaw that is found in mammals with the exception of monotones is no longer independently preserved - the crest and parts of the roof of the skull . MPCA is the abbreviation for the Museo Provincial de Cipolletti Carlos Ameghino , which is located in Cipolletti in the Argentine province of Río Negro .
Systematics
The cladogram suggested by the explorers. The knot in front of Paurodontidae and Meridiolestida has not yet been named.
| Dryolestoidea |
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Diet and Lifestyle
On the basis of the molar teeth found, Rougier suspects that Cronopio mainly fed on insects , larvae , invertebrates and possibly also smaller lizards , which were also discovered at the site. The function of the long canine teeth, however, is difficult to interpret, since such long canine teeth are not found in comparable living animals. Cronopio's skull was rather light and not designed for heavy loads. Cronopio could not use his saber teeth to overwhelm prey because the risk of injury would have been too great.
At the time of Cronopio , the site was a floodplain , populated by large dinosaurs, crocodiles, turtles, sphenodontia and snakes. Little is known about the flora, but some large conifers were found. Floods occurred regularly, possibly leading to the death of the Cronopios .
Christian de Muizon interprets the large eye sockets as an indication that Cronopio was possibly nocturnal .
discovery
In 2002, researchers discovered that in the archaeological site "La Buitrera" Candeleros Formation in the Río Negro province in Argentina a first almost completely enclosed by stone skull. In 2005 they turned the find over to an expert who took three years to uncover the fossil. In 2011 Guillermo W. Rougier, Sebastián Apesteguía and Leandro C. Gaetano published their report on their findings. These are well-preserved skulls and jaws. Normally only teeth and possibly bone fragments are found from the early mammals . Well-preserved skulls, however, are extremely rare. The discovery by Rougier's team also closes a gap for South American mammals with no findings of around 60 million years. Previously, only the skull of Vincelestes neuquenianus , an animal the size of a small opossum that lived 130 million years ago, was known from the time of the dinosaurs .
Trivia
In the press, the resemblance of Cronopio to the "rat squirrel" Scrat from the animated film Ice Age was emphasized. Rougier himself is amused by the similarity. While watching the film, he wondered how the filmmakers could have come up with such a ridiculous animal that had no relation to reality. And then his team would later find such an animal.
literature
- Guillermo W. Rougier, Sebastián Apesteguía & Leandro C. Gaetano (2011): Highly specialized mammalian skulls from the Late Cretaceous of South Americ. Nature 479: 98-102, doi: 10.1038 / nature10591 .
- Fossil discovery: The saber-toothed squirrel actually existed , Zeit Online from November 2, 2011
- Early mammal had saber teeth as of November 2, 2011
Individual evidence
- ↑ a b c d NewScientist of November 2, 2011: Saber-toothed squirrel scurried at dinosaurs' feet
- ↑ Sensation: Researchers find "Scrat". On: Wissenschaft.de from November 2, 2011.
- ^ Guillermo W. Rougier, Sebastián Apesteguía and Leandro C. Gaetano: Highly specialized mammalian skulls from the Late Cretaceous of South America . In: Nature . 479, 2011, pp. 98-102. doi : 10.1038 / nature10591 . Supplementary information page 5 (PDF; 1.4 MB)
- ↑ a b LiveScience of November 2, 2011: Saber-Toothed Squirrel Looked Like 'Ice Age' Scrat
- ↑ National Geographic of November 2, 2011: Ancient "Saber-Toothed Squirrel" Found
- ↑ DiscoveryNews of November 3, 2011: Saber-Toothed Squirrel Lived Near Dinosaurs
- ↑ Spiegel from November 3, 2011: Saber-toothed squirrels roamed Patagonia
- ↑ BBC News of November 2, 2011: Tiny but toothy mammal unearthed