Massospondylus

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Massospondylus
This artistic live representation shows Massospondylus as a two-legged animal.

This artistic live representation shows Massospondylus as a two-legged animal.

Temporal occurrence
Lower Jura ( Hettangian to Pliensbachian )
201.3 to 182.7 million years
Locations
Systematics
Dinosaur (dinosauria)
Lizard dinosaur (Saurischia)
Sauropodomorpha
Massospondylus
Scientific name
Massospondylus
Owen , 1854
species
  • Massospondylus carinatus Owen, 1854
  • Massospondylus kaalae Barrett , 2009

Massospondylus (from ancient Greek μάσσων mássōn "larger" and σφόνδυλος sphóndylos [also σπόνδυλος spóndylos ] "vertebrae, cervical vertebra", literally "longer vertebra") is an original genus of the sauropodomorphic dinosaur . The genus was already described in 1854 by the English anatomist Richard Owen , making it one of the first dinosaurs to be named, even if they were not initially recognized as such. To date, over 80 skeletons are known that come from the Lower Jurassic ( Hettangian to Pliensbachian , about 201 to 183 million years ago) of South Africa , Lesotho and Zimbabwe . This makes Massospondylus one of the best known original Sauropodomorpha.

The type species is Massospondylus carinatus ; seven other species have been named in the past 150 years, of which only Massospondylus kaalae is currently recognized as valid. The exact relationship of Massospondylus is controversial. Often these species is in an as Massospondylidae designated family asked - it is disputed whether and which other dinosaurs to be classified to this group.

Massospondylus reached body lengths of 4 to 5 meters and was characterized by a long neck and tail, a small head and a slender body. It was likely an herbivore , although some researchers suggest it may have been an omnivore . Massospondylus was traditionally portrayed as four-legged , but a 2007 study showed that it was actually a biped . Fossil eggs with skeletons of embryos indicate that newly hatched specimens were four-legged and that the transition to a two-legged way of life only took place in the course of individual development. In addition, these findings suggest parental care.

features

Size comparison with a human
Skull diagram of Massospondylus , showing the different cranial openings ( Eng.External Naris - outer nasal opening, Antorbital Fenstra - Antorbital Window , Orbit - Eye Socket, Supratemopral Fenestra - Upper Temple Window , Lateral Temporal Fenestra - Lateral Temple Window , Mandibular Fenestra - Mandibular Window)

Massospondylus was a medium-sized representative of the original Sauropodomorpha. The body length is estimated at around 4 to 5 meters, the weight in one study at 135 kilograms, in another study at over 200 kilograms. The plan was similar to that of the Plateosaurus , but the skeleton was built lighter overall. The skull was delicate and proportionally smaller than that of Plateosaurus . The neck was relatively longer than that of most other original sauropodomorpha, the vertebral bodies of the anterior cervical vertebrae were four times as long as they were wide, and the forelegs were only half the length of the hind limbs, but quite strong, as indicated by the enlarged upper end of the humerus The hands were short and wide and had five fingers. The fourth and fifth fingers of the hand were significantly smaller and thinner than the other fingers, which gave the hand an asymmetrical appearance. The thumb ended in a greatly enlarged, sickle-shaped claw and was the longest finger of the hand. The foot also ended in five toes, with the fifth toe receding and not touching the ground.

Differences to related genera are mainly found in the skull. This has a proportionally shorter snout and was overall wider and lower than other original Sauropodomorpha - the greatest width of the skull exceeds the height by 10%. The outer surface of the skull had numerous openings ( skull windows ) that reduced weight and provided attachment points for muscles and space for sensory organs. The eye sockets were larger than those of Plateosaurus . The outer nostrils in the front area of ​​the snout were large, as was typical of the original Sauropodomorpha - in Massospondylus they reached about half the size of the eye sockets. The antorbital window , which was smaller than in related genera such as Plateosaurus , was located between the nostril and the eye socket. The two temple windows sat behind the eyes: The lateral temple window ( infratemporal window ) is shaped like an upside-down "T" in Massospondylus , the upper temple window ( supratemporal window ) , which can be seen from above, leaves out the posterior area of ​​the skull. There was also a small window in the lower jaw.

The teeth were leaf-shaped and comparatively long. Their number increased with the size of the skull: in the paired upper jaw there were 14 to 22 teeth on each side, in the paired lower jaw the largest known skull had 26 teeth each. In the premaxillary , a bone in front of the upper jaw, all known specimens had 4 teeth on each side. While the tooth size in the upper jaw decreased towards the back, the teeth in the lower jaw showed a constant size. The lack of signs of wear and the different heights of the teeth shows that the teeth fell out in relatively short time intervals and were replaced by teeth that moved up.

Like other original sauropodomorpha, Massospondylus presumably had cheeks . This is indicated by small openings on the surface of the upper and lower jaw, which contained blood vessels - so in Massospondylus there were only a few, but large openings, while in jawless animals there were numerous small openings. Jaws would have prevented food from falling out of the mouth while eating. Crompton and Attridge (1986) described two skulls with a pronounced overbite and concluded that this difference in length was compensated for by a horny beak (rhamphoteca) sitting on the front of the lower jaw . However, it is controversial whether this overbite is possibly a misinterpretation that is due to the crushing of the fossils. In any case, current studies consider a beak to be unlikely.

Research history

Skull of the neotype specimen (BP / 1/4934) of M. carinatus .

The first fossils were named and described in 1854 by the English anatomist and paleontologist Richard Owen . Owen chose the name Massospondylus ( gr. Masson / μάσσων - "longer"; spondylos / σπόνδυλος "vertebrae"), " because the vertebrae are proportionally longer than those of the extinct crocodile Macrospondylus" (" because the vertebrae are proportionally longer than those of the extinct Crocodile called Macrospondylus ”). At first he did not recognize Massospondylus as a dinosaur, but rather considered it to be a "large, extinct carnivorous reptile" from the relatives of lizards, chameleons and iguanas. The fossils were part of a collection of 56 reptile bones that were discovered in 1853 by the surveyor Joseph Millard Orpen on the site of a farm in the Drakensberg near Harrismith in South Africa and donated to the Royal College of Surgeons of England - since then they have been in the College owned Hunterian Museum kept at the Royal College of Surgeons in London . On May 10, 1941, a bomb attack destroyed the museum, including the fossils, which is why only images and casts of the original material have survived today.

The bones were found outside of the original skeletal structure. Nevertheless, Owen was able to describe three different types of caudal vertebrae, which he assigned to three different genera. According to Owen, the genus Massospondylus showed remarkably long caudal vertebrae, while those of the additionally established genera Pachyspondylus and Leptospondylus are significantly shorter. In addition to vertebrae, the collection also includes various belt and limb bones, which Owen could not assign to any of the three genera. It was later discovered that the bones referred to as the massospondyle tail vertebrae were actually cervical vertebrae, and that all fossils were believed to be of the same species. It may be the remains of two or more specimens.

To date, at least 80 fragmentary skeletons and 4 skulls have been discovered that can be assigned to both young and adult animals. This material comes from the Upper Elliot Formation , the Clarens Formation and the Bushveld Sandstone of South Africa and Lesotho and the Forest Sandstone and the Upper Karroo Sandstone of Zimbabwe . Massospondylus has also been described from the Kayenta Formation of Arizona ( USA ) and from the Canon del Colorado Formation of San Juan ( Argentina ) - however, these fossils have recently been assigned to separate, closely related genera. The evidence from Arizona is based on a well-preserved skull described in 1985. In 2010 this skull was transferred to the new genus Sarahsaurus along with remains of the body skeleton . The Argentine material, which consists of various fragmentary skeletons and at least one skull, was described as Adeopapposaurus in 2009 .

species

The type species described by Richard Owen is M. carinatus . To date, numerous other species have been named, but today, with the exception of M. kaalae ( Barrett , 2009 ), are either synonyms of M. carinatus or the nomina dubia (indeterminable). These no longer recognized species include M. browni ( Seeley , 1895 ), M. harriesi ( Broom , 1911 ), M. hislopi ( Lydekker , 1890 ), M. huenei ( Cooper , 1981 ), M. rawesi ( Lydekker, 1890 ) and M. schwarzi ( Haughton , 1924 ).

M. browni , M. harriesi and M. schwarzi come from the Upper Elliot Formation in the Cape Province in South Africa. All three species are based on fragmentary remnants and are declared as nomina dubia in a review article from 2004 . M. browni is based on two cervical, two dorsal and three caudal vertebrae and various remnants of the hind leg. M. harriesi has been described on the basis of a well-preserved fore limb and parts of the hind limb. M. schwarzi was described using an incomplete hind leg and a sacrum . Fossils from India were referred to as M. hislopi and M. rawesi . M. hislopi based on vertebrae from the Upper Triassic Maleri formation of Andhra Pradesh , M. rawesi on a single tooth from the Upper Cretaceous Takli formation of Maharashtra . The name M. hislopi was temporarily retained in the last review article as a noun dubium belonging to the sauropodomorpha , but M. rawesi could have been a theropod or a non-dinosaur. M. huenei is a new combination that Michael Cooper derived from Lufengosaurus huenei because he considered Lufengosaurus and Massospondylus to be synonyms . However, this synonymity is no longer accepted.

M. kaalae , next to M. carinatus the only currently recognized species, was described in 2009 using a fragmentary skull found in the layers of the Upper Elliot Formation near the village of Voyizane in the Eastern Cape . Various finds of the contemporary Massospondylus carinatus also come from this region . M. kaalae differs from the type species through the morphology of the brain skull and various other skull features, for example the proportions of the premaxillary .

Synonyms

Like all animals, Massospondylus also showed intraspecific (individual) and ontogenetic (age-related) variation, which makes the assignment of certain finds difficult. In the past, a number of genera were described whose differences from other Massospondylus fossils are now attributed to these variations and which are therefore mostly synonymous with Massospondylus . The synonyms include the genera Leptospondylus and Pachyspondylus (Owen, 1854) as well as Aristosaurus , Dromicosaurus , Gryponyx taylori and Hortalotarsus .

Hortalotarsus skirtopodus is based on the remains of a hind leg that was discovered in 1888 near Barkly East in the Eastern Cape and described by Harry Seeley in 1894. Robert Broom (1911) notes:

“Originally most of the skeleton was in the rock, and it was regarded by the farmers as the skeleton of a Bushman, but it is said to have been destroyed through fear that a Bushman skeleton in the rock might tend to weaken the religious belief of the rising generation. "

“Originally, most of the skeleton was in the rock, and it was mistaken for the skeleton of a Bushman by the farmers; however, it is said that it was destroyed for fear that a Bushman skeleton in the rock could weaken the religious beliefs of the rising generation. "

- Broom : 1911

Aristosaurus erectus was described by ECN van Hoepen (1920) and is based on an almost complete, albeit skullless, skeleton that was discovered during mining in a natural stone quarry near Roosendal and bought by the Transvaal Museum in 1915 . Hoepen also described Dromicosaurus gracilis on the basis of a fragmentary skeleton he discovered. Gryponyx taylori was named by Sidney H. Haughton (1924); it is based on the pelvic girdle bones and sacral vertebrae discovered near Fouriesburg in 1915 . All of these species come from the Upper Elliot Formation of South Africa, from which Massospondylus also originates. According to the International Rules for Zoological Nomenclature (ICZN), these are younger synonyms: They were named when Massospondylus was already scientifically described; the name Massospondylus therefore has priority.

Systematics

Cladogram , simplified from Yates (2007)
  Plateosauria  
  Plateosauridae  

 Unaysaurus


   

 Plateosaurus



  Massopoda  
 Riojasauridae  

 Riojasaurus


   

 Eucnemesaurus



  (unnamed)  
  Massospondylidae  

 Massospondylus 


  (unnamed)  

 Coloradisaurus 


   

 Lufengosaurus 




  (unnamed)  

 Jingshanosaurus


   

 Anchisauria (including Sauropoda )






Template: Klade / Maintenance / Style
In this review, Massospondylus was classified as a close relative of Lufengosaurus and Coloradisaurus . The cladogram supports the hypothesis of "extreme prosauropod paraphyly". This is just one of many proposed cladograms for the systematics of the original sauropodomorpha.

The sauropodomorpha are traditionally divided into two groups: the prosauropods and the sauropods . This classification is now considered refuted, as the sauropods are derived from representatives of the classic prosauropods - thus the “prosauropods” include the sauropods and are therefore paraphyletic . Current discussions revolve around the question of how strong this paraphyly is pronounced: Supporters of the "nuclear prosauropod monophyly" are of the opinion that some core groups of the classical prosauropods - the Massospondylidae, the Plateosauridae and the Riojasauridae - form a monophyletic group while Followers of the "extreme prosauropod paraphyly" come to the conclusion that these groups split off independently of each other from the line of development leading to the sauropods.

Massospondylus is often classified within the Massospondylidae family . By definition, this group includes all genera that are more closely related to Massospondylus than to Plateosaurus . The genera to be classified within the Massospondylidae according to this definition and thus the closest relatives of Massospondylus vary depending on the study. Coloradisaurus , Yunannosaurus and Lufengosaurus are often recognized as massospondylids. However, other researchers came to the conclusion that Massospondylus is the only Massospondylid and consider the family to be obsolete.

Occurrence and palaeo-habitat

Massospondylus fossils are from the Karoo supergroup in South Africa , Lesotho and Zimbabwe . This enormous sequence of layers was deposited from the Upper Permian to the Lower Jurassic and is the world's most important continental fossil deposit in this time interval. Massospondylus occurs in the lower Jurassic layers of the Karoo supergroup - the occurrence ranges from the earliest Lower Jurassic immediately above the Triassic-Jura boundary to about 183 million years ago, when enormous lava flows (flood basalts) brought the Karoo supergroup to complete the deposition. Massospondylus is the most frequently found fossil of this as yet little explored stratified interval , which is also known as the Massospondylus range zone .

Massospondylus lived in a fairly dry, desert-like climate. The habitat it announced temnospondyli , turtles , the Sphenodontier Clevosaurus , Rauisuchier , crocodile relatives as Protosuchus and Ornithosuchus , theropod dinosaurs like Megapnosaurus , Ornithopod dinosaurs as Lesothosaurus , Abrictosaurus , Heterodontosaurus , Lycorhinus and pegomastax and various Cynodontiern . In the Upper Elliot Formation and the Clarens Formation, from which a large part of the Massospondylus fossils originate, Massospondylus carinatus was long considered the only known sauropodomorph. However, Paul Barrett (2009) noted that there are at least four other sauropodomorphs, including two sauropods, albeit with fragmentary remains. Recently two more sauropodomorphs from the Upper Elliot Formation were described with Ignavusaurus and Arcusaurus .

Paleobiology

Locomotion and mobility

Assembled massospondyle skeleton (cast) in the Natural History Museum in London in the obsolete four-legged position

For a long time it was assumed that these animals moved mainly quadruped ( walking on four legs). However, a biomechanical study by Matthew Bonnan and Phil Senter published in 2007 came to the conclusion that Massospondylus and the related Plateosaurus were obligately biped , that is, they only moved on two legs. So it was impossible for these animals to pronate the hand (to turn the palm down). This is also indicated by in-situ finds of arms that are still preserved in their original skeletal structure and that always show the palms of the hands facing each other. The very limited range of motion of the arms indicates a bipedal mode of locomotion.

Robert Bakker (1987) suspects that the shoulder blade in quadruple dinosaurs oscillated with the front legs and thus increased the step width as a kind of elongated leg. This feature is found in many modern quadruped mammals and could have compensated for the restricted range of motion of the arms in a quadruped massospondyle . The prerequisite for this, however, is that the collarbones have receded - functional collarbones act like a clasp between the right and left shoulder blades and prevent the rotation of this bone that is relevant for locomotion. In fact, the Ceratopsia group showed greatly reduced collarbones, and the dominant view at the time extended this finding to all dinosaur groups outside the line of development leading to the birds.

A more recent discovery shows, however, that Massospondylus had well-developed collarbones, which were connected at their ends in a V-shape and thus resembled the wishbone of birds. This finding proves that the shoulder girdle was actually relatively static and could not make any relevant active contribution to locomotion. The reduction of the collarbones was consequently an innovation that was limited to the line of development leading to the Ceratopsia. The evidence of collarbones in the massospondylus is also another indication that the wishbone of today's birds emerged from the fusion of the two collarbones.

Michael Cooper (1981) found that the articular processes of the cervical vertebrae were tilted 45 ° from the horizontal. According to this researcher, this led to the fact that the neck allowed vertical, but no lateral movements. The rest of the spine was also very limited in its horizontal mobility, which is why the animal must always have turned the entire body when the neck was turned. Paul Barrett and Paul Upchurch (2007) disagree and state that the articular processes were only tilted at the base of the neck, but were almost horizontal in the anterior cervical vertebrae, which allowed sufficient lateral mobility of the neck.

nutrition

Massospondylus and related genera were likely herbivores or omnivores . The teeth were straight, leaf-shaped, and roughly serrated, making them suitable for chopping up plant-based foods. The tooth crowns were wider than the tooth roots, which reduced the gaps between the teeth so that the row of teeth formed a continuous cutting edge for cutting off plant material. Paul Barrett (2000) notes, however, that the teeth of the premaxillary and the front teeth of the upper jaw differ from the rest of the teeth: These teeth were slightly curved backwards and finely serrated - thus they showed similarities with the teeth of carnivorous dinosaurs. Barrett concluded that as an omnivore , Massospondylus may have supplemented its diet with small prey such as small reptiles, mammals, and invertebrates . Michael Cooper (1981) suggested that some of the food was carrion and speculated that the sickle-shaped hand claw may have been used to break open carcasses.

Raath (1974) reported the discovery of gastroliths (stomach stones) in three massospondylus skeletons from the forest sandstone of Zimbabwe. It has long been assumed that these stones swallowed by animals were used to grind food in the stomach, similar to what is the case with today's birds. Oliver Wings and Martin Sander (2007) showed, however, that these stones could not make a relevant contribution to digestion: The stones were polished and not rough as in birds. In addition, only one of the massospondyle skeletons showed enough gastrolites to form an effective gastric mill.

growth

Skull casts of a juvenile and an adult specimen of M. carinatus

Statements about the growth and the individual age of fossil vertebrates can be derived from growth rings and other structures of the outer bone layer ( cortex ). Massospondylus showed a phase of rapid growth up to the age of 15, in which up to 34.6 kg were put on per year - this rate is comparable to that of recent mammals. In contrast to mammals, however, there was no growth stop; even after the age of 15, the body size continued to increase, albeit at a significantly slower rate.

Martin Sander and Nicole Klein (2005) examined the growth of the closely related genus Plateosaurus and showed that these animals adapted their growth to the respective environmental conditions. With a rich food supply or good climatic conditions, growth was accelerated and the phase of rapid growth was prolonged. This phenomenon, known as development plasticity, occurs today in ectothermic animals such as reptiles. In endothermic (warm-blooded) mammals and birds, on the other hand, growth follows a defined growth curve - the growth rate and final body size vary only slightly between individuals. Plateosaurus is the only dinosaur and thus probably the only known endothermic animal in which developmental plasticity has been proven - all other dinosaurs examined accordingly, including the Massospondyle, correspond to mammals and birds. The researchers conclude: “… [ Plateosaurus ] possibly represents the initial stage in the evolution of metabolic thermoregulation (endothermy) in dinosaurs, in which endothermy was decoupled from developmental plasticity” (“… Plateosaurus possibly represents an initial stage in the evolution of metabolic thermoregulation ( Endothermia) in dinosaurs, in which endothermia and developmental plasticity were still decoupled from each other ”).

Reproduction and development

Cast of a clutch of eggs and embryos in the Royal Ontario Museum in Toronto
Artist's impression of a newly hatched massospondyle as a quadruped

A major find was made in 1976 when paleontologist James Kitching found a block of six fossilized eggs on a road outcrop in South Africa's Golden Gate Highlands National Park . These round eggs, measuring up to 6 cm in diameter, contained the remains of embryos. Such in-ovo- preservation (preservation within eggs) is extremely rare in dinosaurs, in fact this find is the oldest known to this day. The site known today as the Rooidraai site has only been examined more closely by researchers working with Robert Reisz since 2006 , and a total of 10 clutches with eggs were discovered, some also with embryo remains. This discovery offers unique insights into the reproductive and developmental biology of these animals.

All clutches discovered were incomplete; the most complete clutch discovered contained 34 eggs. The clutches were found in at least three different stratigraphic layers. From this it can be concluded that at least two Massospondylus specimens nested at this location at least four different times. How many nests actually existed cannot be determined because of the location on a steep slope. Presumably it was a nesting colony that gathered periodically at this location. The clutches were created in the immediate vicinity of the water in soft sediment, as indicated by bioturbation (burial tunnels created by invertebrates). Presumably the eggs were at least partially buried in the sediment, as indicated by the very thin eggshells, only 0.1 mm thick. The eggshell enables gas to be exchanged between the egg and its surroundings - a thin eggshell ensures gas exchange even in an environment that is poor in oxygen and rich in carbon dioxide. There is no evidence of nest building, but the eggs were closely packed in rows. The size of the adult animals suggests that the eggs were actively pushed into this position by the mother after laying.

The embryo skeletons found probably come from animals that were about to hatch. The embryonic skeleton differs from that of adult animals only in the clearly different proportions. The skull is noticeably large with a short snout and very large eye openings, the diameter of which is 39% of the length of the skull. The cervical vertebrae are short and thus stand in contrast to the greatly elongated cervical vertebrae of adult animals. The pubic bone and ischium, as well as the caudal vertebrae, are proportionally smaller than those of adult skeletons. The significantly longer front limbs are also noticeable. The large head and long forelimbs show that these animals must have moved quadruped after hatching, and that there was a transition to bipedia at a later stage of development, as shown by adults. Skeletons of newly hatched animals are known from another sauropodomorph, Mussaurus . These embryo remains resemble those of Massospondylus , which is why it can be assumed that other original sauropodomorphs were also quadruped at first and only became biped during further development.

The Dinosauria group is derived from bipedal ancestors. Different lines of development within the dinosaurs, including that leading to the sauropods , changed from bipedic to quadruped locomotion. The quadrupedy in the youth stage of Massospondylus allows unique conclusions to be drawn about the evolutionary mechanism that led to the quadrupedy of the sauropods: This transition from a bipedal to a quadruped way of life is therefore due to pedomorphosis , the retention of characteristics originally only present in the youthful stages in adult animals. Reisz and colleagues also discussed the question of why the young animals of the original sauropodomorphic dinosaurs were quadruped when they deviated from the original bipedal state: For example, the neck in the original state was S-shaped, but sauropodomorphs kept it straight as an adaptation to a plant-based diet. According to these researchers, this modification, which shifts the body's center of gravity forward, in interaction with the large heads, could have been responsible for the evolution of the quadrupeds in newly hatched animals.

Although the pups were quadruped after hatching, they showed no adaptations to pronation of the hand, so they could not turn the palm down when the arm was vertical. Together with the small pelvic bones and the large head, this indicates that effective locomotion was not possible. The animals could therefore Nesthocker have been, which presupposes a certain degree of parental care. This interpretation is supported by the lack of teeth in the embryos and by footprints that were found on the clutches and that can be assigned to newly hatched massospondylus . These footprints show both hand and footprints, which confirms the quadruple inferred from the skeletal proportions. The handprints indicate that the palms were facing in and the thumb was facing forward, confirming that the hands were not pronated. In addition, the largest imprints measured around 15 mm, while a newly hatched animal would have left an imprint of only 7 mm, which shows that the animals had remained at the nesting site for some time after hatching.

Web links

Commons : Massospondylus  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c d Bruce S. Rubidge: 27th Du Toit Memorial Lecture. Re-uniting lost continents - Fossil reptiles from the ancient Karoo and their wanderlust. In: South African Journal of Geology. Volume 108, No. 1, 2005, ISSN  0371-7208 , pp. 135-172, doi: 10.2113 / 108.1.135 .
  2. ^ A b Frank Seebacher: A new method to calculate allometric length-mass relationships of dinosaurs. In: Journal of Vertebrate Paleontology. Volume 21, No. 1, 2001, ISSN  0272-4634 , pp. 51-60, doi : 10.1671 / 0272-4634 (2001) 021 [0051: ANMTCA] 2.0.CO; 2 .
  3. ↑ a b c d e f g h i Peter Galton , Paul Upchurch : Prosauropoda. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. a. 2004, ISBN 0-520-24209-2 , pp. 232-258.
  4. ↑ Cecilio C. Vasconcelos, Adam M. Yates: sauropodomorpha biodiversity of the upper Elliot Formation (Lower Jurassic) of southern Africa. In: Geoscience Africa 2004. Abstract Volume 2. University of the Witwatersrand, Johannesburg 2004, ISBN 0-620-32470-8 , p. 670.
  5. ↑ a b Gregory M. Erickson, Kristina Curry Rogers, Scott A. Yerby: Dinosaurian growth patterns and rapid avian growth rates. In: Nature . Volume 412, No. 6845, 2001, pp. 429-433, doi: 10.1038 / 35086558 .
  6. ↑ a b Paul C. Sereno : The origin and evolution of dinosaurs. In: Annual Review of Earth and Planetary Sciences. Volume 25, No. 1, 1997, ISSN 0084-6597 , pp. 435-489, here pp. 436-437, 451, doi: 10.1146 / annurev.earth.25.1.435 .  
  7. ^ Heinrich Mallison: It's time for even more Plateosaurus! (prosauropod proportions). In: dinosaurpalaeo. Retrieved August 8, 2014 .
  8. ↑ a b c d e f g h i Adam M. Yates: Basal Sauropodomorpha: The "Prosauropods". In: Michael K. Brett-Surman, Thomas R. Holtz Jr. , James O. Farlow (Eds.): The Complete Dinosaur. 2nd edition. Indiana University Press, Bloomington IN 2012, ISBN 978-0-253-35701-4 , pp. 425-443.
  9. ↑ a b c d e f Matthew F. Bonnan, Phil Senter: Were the basal sauropodomorph dinosaurs Plateosaurus and Massospondylus habitual quadrupeds? In: Paul M. Barrett , David J. Batten (Eds.): Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (= Special Papers in Palaeontology. Volume 77). The Palaeontological Association, London 2007, ISBN 978-1-4051-6933-2 , pp. 139-155.
  10. ↑ a b c d e f g h i Michael R. Cooper: The Prosauropod Dinosaur Massospondylus carinatus Owen From Zimbabwe: Its Biology, Mode of Life and Phylogenetic Significance (= Occasional Papers of the National Museums and Monuments of Rhodesia. Series B: Natural Sciences, Volume 6, No. 10, ZDB ID 405377-1 ). National Museums and Monuments, Salisbury 1981.
  11. ^ A b Christoper E. Gow, James W. Kitching , Michael A. Raath: Skulls of the prosauropod dinosaur Massospondylus carinatus Owen in the collections of the Bernard Price Institute for Palaeontological Research. In: Palaeontologia Africana. Volume 27, 1990, ISSN  0078-8554 , pp. 45-58, here 54-56.
  12. ^ A b c Hans-Dieter Sues , Robert R. Reisz, Sanja Hinic, Michael A. Raath: On the skull of Massospondylus carinatus Owen, 1854 (Dinosauria: Sauropodomorpha) from the Elliot and Clarens formations (Lower Jurassic) of South Africa. In: Annals of Carnegie Museum. Volume 73, No. 4, 2004, ISSN 0097-4463 , pp. 239-257.  
  13. ^ Alfred W. Crompton , John Attridge: Masticatory apparatus of the larger herbivores during Late Triassic and Early Jurassic times. In: Kevin Padian : The Beginning of the Age of Dinosaurs. Faunal Change Across the Triassic – Jurassic Boundary. Cambridge University Press, Cambridge u. a. 1986, ISBN 0-521-30328-1 , pp 223-236, here pp 227-228.
  14. ^ A b c Paul M. Barrett, Paul Upchurch: The evolution of feeding mechanisms in early sauropodomorph dinosaurs. In: Paul M. Barrett, David J. Batten (Eds.): Evolution and Palaeobiology of Early Sauropodomorph Dinosaurs (= Special Papers in Palaeontology. Volume 77). The Palaeontological Association, London 2007, ISBN 978-1-4051-6933-2 , pp. 98-99.
  15. ↑ a b c d e f Descriptive catalog of the fossil organic remains of Reptilia and Pisces contained in the museum of the Royal College of Surgeons of England. Taylor and Francis, London 1854.
  16. ^ A b c d Adam M. Yates, Paul M. Barrett: Massospondylus carinatus Owen 1854 (Dinosauria: Sauropodomorpha) from the Lower Jurassic of South Africa: Proposed conservation of usage by designation of a neotype. In: Palaeontologia Africana. Volume 45, 2010, pp. 7-10, digital version (PDF; 540 kB)
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  18. ^ A b c Paul M. Barrett: A new basal sauropodomorph dinosaur from the upper Elliot Formation (Lower Jurassic) of South Africa. In: Journal of Vertebrate Paleontology. Volume 29, No. 4, 2009, pp. 1032-1045, doi: 10.1671 / 039.029.0401 .
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