Lazarussuchus
Lazarussuchus | |
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Reconstruction of Lazarussuchus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | †Choristodera |
Genus: | †Lazarussuchus Hecht, 1992 |
Type species | |
†Lazarussuchus inexpectatus Hecht, 1992
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Other species | |
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Lazarussuchus (meaning "
Discovery
The first remains of Lazarussuchus, belonging to the type species L. inexpectatus were described in 1992 from a mostly complete articulated skeleton (Claude Bernard University no Re 437, coll. Gennevaux 92813) found in the Upper Oligocene aged sediments of the Armissan limestone quarry near Narbonne in Aude, France. The genus was named after the "Lazarus Effect", as the remains were the youngest known choristodere fossils, and resembled the most primitive choristodere known, the Middle-Late Jurassic Cteniogenys.[1] In 2005 another species, L. dvoraki, was described from isolated skull bones and vertebrae from the Early-Middle Miocene sediments of the Merkur-North locality in the north-west Czech Republic. The species was named after Zdeněk Dvořák who had collected the specimens.[2] In 2008, remains of Lazarussuchus were reported from the Upper Oligocene sediments of Oberleichtersbach in northern Bavaria, Germany. Remains included 25 bones, and was suggested to probably represent a new species.[4] In 2013, a specimen of Lazurussuchus was described from the late Paleocene aged Menat Formation near Menat, Puy-de-Dôme in France. The specimen, which is an almost complete articulated skeleton (BDL 1819) is largely preserved as an impression, with remnants of disintegrating bone and some preserved soft tissue. The remains were not assigned to a species however, because it could not be robustly diagnosed separately from the two named species.[3] In 2019, in the supplementary information for the paper describing the remains of the extinct ape Danuvius, indeterminate remains of Lazarussuchus were reported from the Hammerschmiede clay pit near Pforzen, Bavaria, Germany. The Hammerschmiede locality has been dated magnetostratigraphically to the base of the Tortonian stage of the Late Miocene, approximately 11.62 million years ago.[5]
Description
Lazarussuchus was small and superficially
L. inexpectatus is distinguished by having the postparietal processes of the parietal bone equal or nearly equal in length to the parietal plate, directed posteriorly with less than 30 degrees of angulation and only weakly concave, resulting in the upper temporal fenestra being elongated and almost rectangular in shape, with an anterior-posterior long axis, nine cervical vertebrae are present, the posterior portion of the trunk vertebrae have spinous processes below the postzygapophyses that act as additional articular surfaces, four functional sacral vertebrae are present, of which the first is a sacrodorsal, and a slender T-shaped interclavicle. L. dvoraki is distinguished by having postparietal processes only 1/3 of the length of the parietal plate, which are angulated greater than 45 degrees laterally and a concave lateral margin, resulting in the upper temporal fenestrae being smaller and more ovoid in comparison to L. inexpectatus, with a antero-medial to posterolateral long axis, and the trunk vertebrae lack articular spinal processes.[3]
The Menat specimen is distinguished by having 40 maxillary teeth and a total of 52 teeth in the upper jaw as opposed to 11 premaxillary and 24 maxillary tooth positions in L. inexpectatus, however, it cannot be ruled out that these are due to
The premaxilla of the Oberleichtersbach Lazarussuchus is shorter than that of L. inexpectatus, alongside other unspecified cranial bone differences.[4]
Soft tissue
The Menat specimen of Lazarussuchus preserves some remnants of soft tissue, but no scales, which shows that the hindfoot (pes) was not webbed, and a dark stained region with a crenellated edge is present above the caudal vertebrae of the tail, suggestive of a crest similar to those found in some living reptiles, like the tuatara, lizards and crocodiles.[3]
Age and relationships
Lazarussuchus is the youngest member of the group Choristodera and the only choristodere to have lived after the
Lazarussuchus was initially interpreted as the basalmost member of Choristodera, meaning that its lineage must have been the earliest to branch off from the group.
Phylogeny from the analysis of Dong and colleagues (2020):[8]
Choristodera |
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Paleoecology
Although no gut contents have been found, Lazarussuchus is assumed to have fed on invertebrates.[6] At Oberleichtersbach and Merkur-North, Lazaurussuchus was found in continental lake deposits, with a subtropical climate. Occurring alongside fish, frogs, turtles, squamates and alligatoroid crocodillians belonging to the genus Diplocynodon.[9]
References
- ^ .
- ^ S2CID 84097919.
- ^ S2CID 129438118.
- ^ a b Böhme, M. Ectothermic vertebrates (Teleostei, Allocaudata, Urodela, Anura, Testudines, Choristodera, Crocodylia, Squamata) from the Upper Oligocene of Oberleichtersbach (Northern Bavaria, Germany). Courier Forschungsinstitut Senckenberg 260, 161–183 (2008).
- S2CID 207888156.
- ^ ISBN 978-1-4613-6248-7.
- ^ Matsumoto, Ryoko; Dong, Liping; Wang, Yuan; Evans, Susan E. (2019). "The first record of a nearly complete choristodere (Reptilia: Diapsida) from the Upper Jurassic of Hebei Province, People's Republic of China". Journal of Systematic Palaeontology. 0 (0): 1–18. doi:10.1080/14772019.2018.1494220.
- ^ S2CID 219047160.
- .
External links
- Ghost lineages - brief article on the fossil record of choristoderes