Dysalotosaurus

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Dysalotosaurus
Temporal range: Late Jurassic, 152–151  Ma
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D. lettowvorbecki.jpg
D. lettowvorbecki skeleton in Berlin
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Ornithischia
Clade: Ornithopoda
Superfamily: Dryosauroidea
Family: Dryosauridae
Genus: Dysalotosaurus
Virchow, 1919
Species:
D. lettowvorbecki
Binomial name
Dysalotosaurus lettowvorbecki
Virchow, 1919

Dysalotosaurus ("uncatchable lizard") is a genus of herbivorous iguanodontian dinosaur. It was a dryosaurid iguanodontian, and its fossils have been found in late Kimmeridgian-age rocks (Late Jurassic) of the Tendaguru Formation of Lindi Region in Tanzania. The type and only species of the genus is D. lettowvorbecki. This species was named by Hans Virchow in 1919 in honor of the Imperial German Army Officer, Paul von Lettow-Vorbeck. [1] For much of the 20th century the species was referred to the related and approximately contemporary genus Dryosaurus , but newer studies reject this synonymy. [2] [3]

Contents

Discovery and naming

Thousands of Dysalotosaurus bones and bone fragments have been recovered from the Tendaguru Formation in Tanzania, Africa since 1909; [1] the specimens described by Hans Virchow (1919) were discovered between 1909 and 1913. [1] [4] It has been suggested that all of these specimens were part of a herd that was killed in a mass death event. [5] The genus was named by Hans Virchow in 1919, [1] as opposed to Josef Felix Pompeckj (1920), who is often incorrectly cited as naming the genus. [4]

Description

Dysalotosaurus was a small, relatively basal iguanodontian ornithopod. It lacked the large thumb spikes found in later iguanodontians, and was more adapted for bipedalism than its larger relatives with its short front limbs and long, counter-balancing tail. Dysalotosaurus had powerful and long hind limbs, suggesting it was relatively cursorial compared to Iguanodon and other members of the clade.

Based on CT scans of the braincase, it is believed that Dysalotosaurus held its head dorsally (pointing straight forward) when not feeding. The same study also suggested, based on the morphology of the inner ear, that Dysalotosaurus was not able to discern between high- and low-frequency sounds (like most herbivorous dinosaurs). However, it also had other adaptations that are commonly associated with derived hearing abilities, rendering its sensory capabilities unclear. [6]

In 2016, Gregory S. Paul estimated Dysalotosaurus' length at 2.5 metres (8.2 ft), and its weight at 80 kilograms (180 lb). [7]

Ontogeny

Various specimens of Dysalotosaurus are known, all representing animals that were not yet sexually mature at the time of their deaths. [8] Ontogenetic studies demonstrate typical aging trends, such as a lengthening of the snout and relative shrinking of the orbit. Differences in dentition as the animals aged also suggest a change from an omnivorous diet early in life to fully herbivorous feeding habits as an adult. [2] This switch reflects the general evolutionary trend towards obligate herbivory among iguanodontians and other ornithopods.

Dysalotosaurus also appears to have had a life expectancy of roughly twenty years and lived in herds of mixed ages. [9]

Palaeobiology

Side view of skeleton Dryosaurus lettowvorbecki skeleton.jpg
Side view of skeleton

Dysalotosaurus was a precocial dinosaur, which experienced sexual maturity at ten years, had an indeterminate growth pattern, and maximum growth rates comparable to a large kangaroo. [5]

Palaeopathology

In 2011 paleontologists Florian Witzmann and Oliver Hampe from the Museum für Naturkunde and colleagues discovered that deformations of some Dysalotosaurus bones were likely caused by a viral infection similar to Paget's disease of bone. This is the oldest evidence of viral infection known to science. [10]

The discovery of a hemivertebra (spinal malformation) in another specimen likely caused scoliosis and other pathologic effects on the animal during its life. [11] This malformation occurs in almost every vertebrate clade, though this is the first known evidence of the condition in dinosaurs.

Palaeoecology

Contemporary dinosaurs were Kentrosaurus , various sauropods including Giraffatitan and Dicraeosaurus , and large theropods including Megalosaurus and Ceratosaurus . Pterosaurs are also common in the Tendaguru Formation, as well as mammaliaformes (ancestral to mammals).

During the Jurassic, Tendaguru was part of the semi-arid coastline of Gondwana. Dysalotosaurus fossils were discovered in strata that were deposited in structures characteristic of tidal flats and lagoons. [12]

Related Research Articles

<i>Kentrosaurus</i> Extinct genus of dinosaurs from late Jurassic in Lindi Region, Tanzania

Kentrosaurus is a genus of stegosaurid dinosaur from the Late Jurassic in Lindi Region of Tanzania. The type species is K. aethiopicus, named and described by German palaeontologist Edwin Hennig in 1915. Often thought to be a "primitive" member of the Stegosauria, several recent cladistic analyses find it as more derived than many other stegosaurs, and a close relative of Stegosaurus from the North American Morrison Formation within the Stegosauridae.

<i>Dryosaurus</i> Extinct genus of dinosaurs

Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont. Fossils have been found in the western United States and were first discovered in the late 19th century. Valdosaurus canaliculatus and Dysalotosaurus lettowvorbecki were both formerly considered to represent species of Dryosaurus.

<span class="mw-page-title-main">Hypsilophodontidae</span> Extinct family of dinosaurs

Hypsilophodontidae is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from the Middle Jurassic until the Late Cretaceous. This inclusive status was supported by some phylogenetic analyses from the 1990s and mid 2000s, although there have also been many finding that the family is an unnatural grouping which should only include the type genus, Hypsilophodon, with the other genera being within clades like Thescelosauridae and Elasmaria. A 2014 analysis by Norman recovered a grouping of Hypsilophodon, Rhabdodontidae and Tenontosaurus, which he referred to as Hypsilophodontia. All other analyses from around the same time have instead found these latter taxa to be within Iguanodontia.

<span class="mw-page-title-main">Iguanodontia</span> Extinct clade of dinosaurs

The Iguanodontia are a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include Camptosaurus, Dryosaurus, Iguanodon, Tenontosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodontians were one of the first groups of dinosaurs to be found. They are among the best known of the dinosaurs, and were among the most diverse and widespread herbivorous dinosaur groups of the Cretaceous period.

Callovosaurus is a genus of iguanodontian dinosaur known from most of a left thigh bone discovered in Middle Jurassic-age rocks of England. At times, it has been considered dubious or a valid genus of basal iguanodontian, perhaps a dryosaurid.

<i>Altirhinus</i> Extinct genus of dinosaurs

Altirhinus is a genus of hadrosauroid ornithopod dinosaur from the Early Cretaceous period of Mongolia.

<i>Giraffatitan</i> Sauropod dinosaur genus from the late Jurassic Period in Lindi Region, Tanzania

Giraffatitan is a genus of sauropod dinosaur that lived during the late Jurassic Period in what is now Lindi Region, Tanzania. It was originally named as an African species of Brachiosaurus (B. brancai), but this has since been moved to its own genus. Giraffatitan was for many decades known as the largest dinosaur but recent discoveries of several larger dinosaurs prove otherwise; giant titanosaurians appear to have surpassed Giraffatitan in terms of sheer mass. Also, the sauropod dinosaur Sauroposeidon is estimated to be taller and possibly heavier than Giraffatitan.

<i>Elaphrosaurus</i> Ceratosaurian theropod dinosaur genus from the Late Jurassic Period

Elaphrosaurus is a genus of ceratosaurian theropod dinosaur that lived approximately 154 to 150 million years ago during the Late Jurassic Period in what is now Tanzania in Africa. Elaphrosaurus was a medium-sized but lightly built member of the group that could grow up to 6.2 m (20 ft) long. Morphologically, this dinosaur is significant in two ways. Firstly, it has a relatively long body but is very shallow-chested for a theropod of its size. Secondly, it has very short hindlimbs in comparison with its body. Phylogenetic analyses indicate that this genus is likely a ceratosaur. Earlier suggestions that it is a late surviving coelophysoid have been examined but generally dismissed. Elaphrosaurus is currently believed to be a very close relative of Limusaurus, an unusual beaked ceratosaurian which may have been either herbivorous or omnivorous.

<i>Anabisetia</i> Extinct genus of dinosaurs

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<i>Cumnoria</i> Extinct genus of dinosaurs

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<i>Kangnasaurus</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">Dryosauridae</span> Extinct family of dinosaurs

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<i>Elrhazosaurus</i> Extinct genus of dinosaurs

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<span class="mw-page-title-main">Ankylopollexia</span> Extinct clade of dinosaurs

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<i>Ostafrikasaurus</i> Genus of theropod dinosaur

Ostafrikasaurus is a genus of theropod dinosaur from the Late Jurassic period of what is now Lindi Region, Tanzania. It is known only from fossil teeth discovered sometime between 1909 and 1912, during an expedition to the Tendaguru Formation by the Natural History Museum of Berlin. Eight teeth were originally attributed to the dubious dinosaur genus Labrosaurus, and later to Ceratosaurus, both known from the North American Morrison Formation. Subsequent studies attributed two of these teeth to a spinosaurid dinosaur, and in 2012, Ostafrikasaurus crassiserratus was named by French palaeontologist Eric Buffetaut, with one tooth as the holotype, and the other referred to the same species. The generic name comes from the German word for German East Africa, the former name of the colony in which the fossils were found, while the specific name comes from the Latin words for "thick" and "serrated", in reference to the form of the animal's teeth.

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References

  1. 1 2 3 4 Virchow, Hans (1919). Atlas und Epistropheus bei den Schildkröten. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 8: 303–332.
  2. 1 2 Hübner, T.R.; Rauhut, O.W.M. (2010). "A juvenile skull of Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia), and implications for cranial ontogeny, phylogeny, and taxonomy in ornithopod dinosaurs". Zoological Journal of the Linnean Society. 160 (2): 366–396. doi: 10.1111/j.1096-3642.2010.00620.x .
  3. McDonald, A.T.; Kirkland, J.I.; DeBlieux, D.D.; Madsen, S.K.; Cavin, J.; Milner, A.R.; Panzarin, L. (2010). "New basal iguanodonts from the Cedar Mountain formation of Utah and the evolution of thumb-spiked dinosaurs". PLOS ONE. 5 (11): e14075. Bibcode:2010PLoSO...514075M. doi: 10.1371/journal.pone.0014075 . PMC   2989904 . PMID   21124919.
  4. 1 2 Maier, G (2003). African Dinosaurs Unearthed. The Tendaguru Expeditions. Bloomington: Indiana University Press. p. 432. ISBN   978-0-253-34214-0.
  5. 1 2 Hübner, T.R. (2012). Laudet, V. (ed.). "Bone histology in Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia)--variation, growth, and implications". PLOS ONE. 7 (1): e29958. Bibcode:2012PLoSO...729958H. doi: 10.1371/journal.pone.0029958 . PMC   3253128 . PMID   22238683.
  6. Sobral, G.; Hipsley, C.A.; Müller, J. (2012). "Braincase redescription of Dysalotosaurus lettowvorbecki (Dinosauria, Ornithopoda) based on computed tomography". Journal of Vertebrate Paleontology. 32 (5): 1090–1102. Bibcode:2012JVPal..32.1090S. doi:10.1080/02724634.2012.693554. ISSN   0272-4634. S2CID   85270708.
  7. Paul, G.S. (2016). The Princeton Field Guide to Dinosaurs: Second Edition. Princeton, New Jersey: Princeton University Press. p. 313. ISBN   978-0-691-16766-4.
  8. Hübner, T. (2018). "The postcranial ontogeny of Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia) and implications for the evolution of ornithopod dinosaurs". Palaeontographica Abteilung A. 310 (3–6): 43–120. Bibcode:2018PalAA.310...43H. doi:10.1127/pala/2018/0072. ISSN   0375-0442. S2CID   134500821.
  9. Hübner TR, Foth C, Heinrich WD, Schwarz D, Bussert R (2021). "Research history, taphonomy, and age structure of a mass accumulation of the ornithopod dinosaur Dysalotosaurus lettowvorbecki from the Upper Jurassic of Tanzania". Acta Palaeontologica Polonica. 66 (2): 275–300. doi: 10.4202/app.00687.2019 . S2CID   236713607.
  10. Witzmann, F.; Claeson, K.M.; Hampe, O.; Wieder, F.; Hilger, A.; Manke, I.; Niederhagen, M.; Rothschild, B.M.; Asbach, P. (2011). "Paget disease of bone in a Jurassic dinosaur". Current Biology. 21 (17): R647–8. doi: 10.1016/j.cub.2011.08.006 . PMID   21920291.
  11. Witzmann, F.; Asbach, P.; Remes, K.; Hampe, O.; Hilger, A.; Paulke, A. (2008). "Vertebral Pathology in an Ornithopod Dinosaur: A Hemivertebra in Dysalotosaurus lettowvorbecki from the Jurassic of Tanzania". The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology. 291 (9): 1149–1155. doi: 10.1002/ar.20734 . PMID   18536052. S2CID   21995077.
  12. Bussert, R.; Heinrich, W-D.; Aberhan, M. (2009). "The Tendaguru Formation (Late Jurassic to Early Cretaceous, southern Tanzania): definition, palaeoenvironments, and sequence stratigraphy" (PDF). Fossil Record. 12 (2): 141–174. doi: 10.1002/mmng.200900004 .