Massospondylus
Name:
Massospondylus
(longer vertebra).
Phonetic: Mas-so-spon-de-lus.
Named By: Richard Owen - 1854.
Synonyms:Possibly Aetonyx,
Aristosaurus, Dromicosaurus, Gyposaurus, Hortalotarsus,
Ignavusaurus, Leptospondylus, Pachyspondylus.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Plateosauria, Massopoda,
Massospondylidae.
Species: M. carinatus (type), M.
kaalae.
Diet: Herbivore?
Size: Between 4 and 6 meters long.
Known locations: Lesotho - Upper Elliot
Formation, South Africa - Clarens Formation, Upper Elliot
Formation, and Zimbabwe - Forest Sandstone Formation, Mpandi
Formation, Upper Karroo Sandstone Formation.
Time period: Hettangian to Pliensbachian of the
Jurassic.
Fossil representation: Many individuals.
Massospondylus
was one amongst the first dinosaurs to be named with a taxonomic
history going back as far as the mid nineteenth century. Yet when
Richard Owen described the first fossils, he thought that he was
dealing with an ancient ancestor to more familiar lizards such as
iguanas chameleons. In actuality Massospondylus
represents a genus of
sauropodomorph
dinosaur, a group of dinosaurs that links the later
sauropods
to their bipedal saurischian ancestors.
Partly
due to its long age and also a lack of understanding about dinosaurs in
the early years of palaeontology, Massospondylus
ended up with more
fossil material than was necessary, resulting in a large number of
species being established for the genus. Studies by later
palaeontologists however have now found that many of these species
actually represent other genera, leaving only the type species M.
carinatus, as well as one other species M.
kaalae being valid as
of 2014. Some other genera of sauropodomorph dinosaurs have also
been considered to be synonyms to Massospondylus,
though opinions as
to which are correct varies between different palaeontologists.
As
stated above, Massospondylus was a sauropodomoprh
dinosaur, though
older texts may reference the genus as a prosauropod, the old name
for describing the sauropodomoprhs that has now fallen out of favour by
palaeontologists. The sauropodomorph dinosaur like Massospondylus
are
somewhere between early theropod dinosaurs and later sauropods, and
exactly which side they are closer to depends more upon the genus.
Massospondylus is currently thought to have been
more bipedal
(mostly walking on two legs), though many other sauropodomorphs
were more quadrupedal. The neck of Massospondylus
was quite long,
even when compared to other sauropodomorphs.
Size
estimates for Massospondylus range between four and
six meters long,
and depending upon the validity of the fossils being measured, may
indicate that the size of Massospondylus was highly
variable. Size
variation is not that unusual in sauropodomorph dinosaurs though,
with the genus Thecodontosaurus
being estimated between one and two
and a half meters long, and Anchisaurus
being two meters long, but
possibly as much as four meters if the genus Ammosaurus
is a synonym to
it. If Massospondylus grew mostly to around 4
meters long then
the genus would be comparable to others like Seitaad
and Sarahsaurus.
However other genera such as Aardonyx
and Efraasia
are estimated to
have been around six meters long, meaning that larger sauropodomorph
dinosaurs were not uncommon.
Massospondylus
has been considered to have grown in relation to food availability, a
theory that has also been proposed for its more famous relative
Plateosaurus.
What this means is that when food was plentiful, more
energy was available for growth, and so individual Massospondylus
grew larger during these times. When food was scarce however,
growth may have been stunted through lack of nutrients and energy that
supported bone growth. What is known to us though is that
Massospondylus grew for a long time with one studied
specimen being
revealed in a 2001 study by Erickson et al to have come from an
individual Massospondylus that was fifteen years
old, and yet was
still growing at the time of death.
Massospondylus
is noted for having two kinds of teeth, small pointed teeth similar
to those of the theropods in the anterior (front) part of the
mouth, and spatulate teeth in the posterior (rear) of the mouth.
This mix of teeth are the main cause of contention in determining the
diet of Massospondylus, and indeed many other
sauropodomorph
dinosaurs, as the two forms would have enabled them eat anything from
meat to plants. The spatulate teeth of Massospondylus
at least show a
shift towards a more herbivorous diet, and studies of the skull and
jaw mechanics of Massospondylus and other
sauropodomorphs indicate that
these dinosaurs were better adapted to a herbivorous diet. There
continues to be speculation however that sauropodomorphs like
Massospondylus may have still fed upon carrion and
possibly even small
vertebrates like lizards, especially if alternative plant sources
were scarce. The number of teeth varies between Massospondylus,
with those that have larger skulls having more teeth.
There
has frequently been questions as to whether sauropodomoprhs and even
sauropods used gastroliths to aid digestion, and for Massospondylus
rounded stones that may have been used as gastroliths have been found
with at least one specimen. A 2007 study by Wings and Sander
however came to the conclusion that gastroliths were not used by
sauropod dinosaurs. Gastroliths however do seem to have been used by
some dinosaur genera however, with the theropod Lourinhanosaurus
being one.
The
skulls of Massospondylus have the revealed the
placement of large blood
vessels that quite likely supplied oxygenated blood to cheeks. These
cheeks would have covered the sides of the mouth much like your own,
and prevented food from falling out while it was being processed by
the teeth. This also supports a more herbivorous diet as plant
material usually needs to be chewed before eaten, especially if
there were now gastroliths present.
Massospondylus
is believed to have had at least a partially avian-like respiratory
system, however, like other sauropodomorphs, Massospondylus
does
not show pneumatic opening in the bones, openings which are more
clearly visible within theropods and sauropods. Instead air sacs in
Massospondylus are believed to have been more within
the body.
Despite the lack of bone evidence for this system, Massospondylus
and other sauropodomorphs almost certainly had an avian-like system.
More intensive studies of such systems dating back to the late
twentieth and early twenty-first century have now revealed that the
avian style system of respiration goes as far back as dinosauromorphs
and possibly even earlier archosaurs.
Clutches
of Massospondylus eggs are known and study of these
have revealed the
embryos that were inside of them. From this we now know that newly
hatched Massospondylus would have been quadrupedal
and not bipedal
until older. Newly hatched Massospondylus also
lacked teeth. The
arrangement of the eggs also shows that the eggs were thin shelled and
pushed together by the parent Massospondylus.
Beyond this there is no
evidence for extensive nest building.
The
mid-sized theropod Dracovenator
lived at the same approximate time and
location as Massospondylus, and may have been a
predator. If this
is true, then this would mean that the early Jurassic of Southern
Africa resembled the early Jurassic of North America where predators
like Dilophosaurus,
a relative to Dracovenator, probably hunted
sauropodomorph dinosaurs too.
Further reading
- Descriptive catalogue of the Fossil organic remains of Reptilia and
Pisces contained in the Museum of the Royal College of Surgeons of
England. - London 1-184 - Richard Owen - 1854.
- Note on certain vertebrate remains from the Nagpur district -
Records of the Geological Survey of India 23 (1): 21–24.
- Richard Lydekker - 1890.
- On the type of the genus Massospondylus and on
some Vertebrae and
limb-bone of M. (?) browni - Annals and Magazine of Natural
History 15: 102–125. - H. G. Seeley - 1895.
- On the dinosaurs of the Stormberg, South Africa - Annals of
the South African Museum 7 (4): 291–308. - Robert Broom
- 1911.
- The fauna and stratigraphy of the Stormberg Series - Annals of
the South African Museum 12: 323–497. - Sydney H. Haughton
- 1924.
- 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 6 (10): 689–840.
- M. R. Cooper - 1980.
- The southern Liassic prosauropod Massospondylus
discovered in North
America - Journal of Vertebrate Paleontology 5 (2):
128–132. - J. Attridge, A. W. Crompton & F.
A.
Jenkins Jr.- 1985.
- Skulls of the prosauropod dinosaur Massospondylus
carinatus Owen in
the collections of the Bernard Price Institute for Palaeontological
Research - Palaeontologia Africana 27: 45–58. - C. E.
Gow, J. W. Kitching & M. K. Raath - 1990.
- Morphology and growth of the Massospondylus
braincase (Dinosauria,
Prosauropoda) - Palaeontologia Africana 27: 59–75. - C.
E. Gow - 1990.
- Ontogenetic growth of the dinosaurs Massospondylus
carinatus and
Syntarsus rhodesiensis". In: Abstracts of
papers. Society of
Vertebrate Paleontology, fifty-second annual meeting. Royal Ontario
Museum Toronto, Ontario - Journal of Vertebrate Paleontology
12 (3): 23A. - A. Chinsamy - 1992.
- The first South American record of Massospondylus
(Dinosauria:
Sauropodomorpha) - Journal of Vertebrate Paleontology, Abstracts
of papers. Society of Vertebrate Paleontology, 20–23 October,
19, Suppl. 3, 61A. - R. Martinez - 1999.
- Massospondylus (Dinosauria:
Sauropodomorpha) in northwestern
Argentina - Abstracts VII International Symposium on Mesozoic
Terrestrial Ecosystems, Buenos Aires, 40. - R. N. Martinez
- 1999.
- Dinosaurian growth patterns and rapid avian growth rates -
Nature 412 (6845): 429–433. - Gregory M. Erickson,
Kristina Curry Rogers & Scott A. Yerby - 2001.
- The cranial anatomy of Massospondylus carinatus
Owen, 1854 and
its implications for prosauropod phylogeny - Journal of Vertebrate
Paleontology. Abstracts of papers. Society of Vertebrate
Paleontology, 22, Supplement to number 3, 65A. - S.
Hinic - 2002.
- On the skull of Massospondylus carinatus Owen,
1854
(Dinosauria: Sauropodomorpha) from the Elliot and Clarens
formations (Lower Jurassic) of South Africa - Annals of
Carnegie Museum 73 (4): 239–257. - H. -D. Sues, R.
R. Reisz, S. Hinic & M. Raath - 2004.
- Furcula-like clavicles in the prosauropod dinosaur Massospondylus
- Journal of Vertebrate Paleontology 25 (2): 466–468. -
Adam M. Yates & Cecilio C. Vasconcelos - 2005.
- Developmental plasticity in the life history of a prosauropod
dinosaur - Science 310 (5755): 1800–1802. - Martin
P. Sander & Nicole Klein - 2005.
- Basic avian pulmonary design and flow-through ventilation in
non-avian theropod dinosaurs - Nature 436 (7048):
253–256. - Patrick M. O'Connor & Leon P. A. M.
Claessens - 2006.
- Were the basal sauropodomorph dinosaurs Plateosaurus
and
Massospondylus habitual quadrupeds? - In Paul
M. Barrett
&
D. J. Batten (eds.). Evolution and Palaeobiology of Early
Sauropodomorph Dinosaurs. Special Papers in Palaeontology 77.
London: The Palaeontological Association. pp. 139–155. -
Matthew S. Bonnan & Phil Senter - 2007.
- No gastric mill in sauropod dinosaurs: new evidence from analysis
of gastrolith mass and function in ostriches - Proceedings of the
Royal Society B: Biological Sciences 274 (1610): 635–640.
- O. Wings & P. Martin Sander - 2007.
- What pneumaticity tells us about 'prosauropods', and vice
versa. - Special Papers in Palaeontology 77: 207–222. -
Mathew Wedel - 2007.
- A new basal sauropodomorph dinosaur from the Upper Elliot
Formation (Lower Jurassic) of South Africa - Journal of
Vertebrate Paleontology 29 (4): 1032–1045. - P. M.
Barret - 2009.
- Embryonic Skeletal Anatomy of the Sauropodomorph Dinosaur
Massospondylus from the Lower Jurassic of South
Africa - Journal of
Vertebrate Paleontology 30 (6): 1653, 1664 - Robert R.
Reisz, David C. Evans, Hans-Dieter Sues & Diane Scott
-
2010.
- Massospondylus carinatus Owen 1854
(Dinosauria:
Sauropodomorpha) from the Lower Jurassic of South Africa: Proposed
conservation of usage by designation of a neotype - Palaeontologia
Africana 45: 7–10. - Adam M. Yates & Paul M.
Barret - 2010.
Reassessment of the Evidence for Postcranial Skeletal Pneumaticity in
Triassic Archosaurs, and the Early Evolution of the Avian Respiratory
System - Plosone - Richard J. Butler, Paul M. Barret,
David J. Gower - 2012.
----------------------------------------------------------------------------
Random favourites
 |
 |
 |
 |