Classification of the Sauropodomorpha after Wilson, J. A. and P. C. Sereno. 1998. Early
evolution and higher-level phylogeny of sauropod dinosaurs. Journal of Vertebrate
Paleontology 18, supplement to number 2; Society of Vertebrate Paleontology, Memoir
Upchurch, P. 1998. The phylogenetic relationships of sauropod
dinosaurs. Zoological Journal of the Linnean Society: 124:43-103.
Wilson, Jeffrey A. 2001. Sauropod dinosaur phylogeny: critique and cladistic analysis. Zoological Journal of the Linnean Society, 136: 217-276
- distinctly asymmetrical manus with digit II the longest digit [D&R
saurischian pelvis (primitive)
- elongate caudal cervicals giving a long neck
- antorbital fenestra well-developed
- large quadratojugal; temporal musculature extends onto frontal
- relatively small skull, with retracted enlarged nares
- very long neck
- one to three extra sacral vertebrae
- enormous pollex (thumb) with an enlarged claw
- spatulate teeth; herbivores
- gastroliths to aid digestion. (also occur in two theropods)
- Saturnalia, Prosauropoda, and Sauropoda
- This primitive sauropodomorph from the upper Triassic (Carnian) of Brazil
is one of the earliest occuring dinosaurs. It was lightly built and
small (1.5 m long).
sauropodomorphs that were the dominant large herbivores of the late Triassic and early Jurassic
- small to medium size
- quadrupedal or bipedal, but primarily bipedal
- low jaw joint for sustained and evenly spread bite.
- traditionally interpreted as a paraphyletic group ancestral to the
- Synapomorphies uniting prosauropods as a monophyletic group include a twisted
pollex with a large inwardly pointing claw.
about 6-8 m long
- Thecodontosaurus, about 1.2 m long
(late Triassic to latest Cretaceous)
Illustration from O. C. Marsh.
1896. The dinosaurs of North America.
the earliest sauropod, is represented by an incomplete skeleton from the Late Triassic
of Thailand, providing the first osteological evidence of pre-Jurassic sauropods.
dinosaur is markedly different from prosauropods and substantiates theoretical predictions that there was a fairly long period of sauropod
evolution during the Triassic." E. Bufffetaut, V. Suteethorn, G. Cuny,
H. Tong, J. Le Loeuff, S. Khansubha, & S. Jongautchariyakul. 2000.
The earliest known sauropod dinosaur. Nature 407, 72 - 74.
- very large, quadrupedal herbivores
- limb bones greatly thickened, solidly ossified (columnar)
- graviportal feet
- sauropods as suspension
- dorsal vertebrae converted to cervicals, elongating neck
nesting grounds [Chiappe, L. M., R. A. Coria, L. Dingus, F. Jackson, A. Chinsamy, and M. Fox. 1998. Sauropod dinosaur embryos from the late Cretaceous of Patagonia. Nature 396:258-261]
- primitive sauropods ("cetiosaurs") plus Neosauropoda
"Cetiosauridae" [middle Jurassic]
- a paraphyletic group of primitive sauropods
- shortened postorbital region of skull
- elongate necks
- short and massive limb bones
- Wilson and Sereno (1998) include Shunosaurus and the neosauropods in the
Eusauropoda because of the collapse of the pes into a graviportal stance from a
digititigrade stance in the eusauropods.
- elevation of the metacarpus from a plantigrade to digitigrade posture
- Diplodocoidea + Macronaria (=Camarosauromorpha)
- the longest dinosaurs
- long whip-like tails (possibly used for
- slender, peg-like teeth at front of mouth only
- high vertebral spines
- Latest Jurassic-late Cretaceous
Diplodocus--Illustration from O. C. Marsh.
1896. The dinosaurs of North America
en = external nares
- arched internarial bar formed by a narrow premaxilla; clearly defined snout
- Camarasaurus plus Titanosauriformes
Illustration from C. W. Gilmore.
1925. A nearly complete articulated skeleton of Camarasaurus....
en = external nares
- short heavy skull
- nostrils open outward
- large, spoon-shaped teeth
- Brachiosauridae plus Titanosauroidea
Brachiosauridae (middle Jurassic - lower Cretaceous)
- elevated nasals
- elongate forelimb
- weights up to 80,000 kilograms (perhaps)
- 22-30 m long; head would have been 13 m above the ground; 30-?80 tons
altithorax was first described on the basis of an
incomplete skeleton discovered in the Morrison Formation of
Colorado. A few years later five relatively complete
skeletons were found at Tendaguru in Tanzania.
was to be the name a giant sauropod from the Late Jurassic, Morrison Formation, Western USA.
However this name was first used for a misidentified Korean
dinosaur. The Morrison brachiosaur, when it was finally named,
was called Ultrasauros macintoshi. This species is
probably Brachiosaurus altithorax.
- This dinosaur from the early Cretaceous of Oklahoma was perhaps the tallest. With its head raised, it stood
nearly 20 m tall. However, it is known only from ribs and
cervical vertebrae. [Wedel, Cifelli & Sanders, 2000 Journal of
Vertebrate Paleontology 20:109-114]
- steeply sloping quadrate, long broad snout with a small number of cylindrical teeth
Titanosauridae - [?upper
Jurassic, upper Cretaceous]
- dermal armor
- poorly known
possibly the largest dinosaur ever discovered
- 21 m; 30 tonnes
- The last sauropod from North America (late Cretaceous)
- probably an immigrant from South America, following the
mid-Cretaceous extinction of the brachiosaurids in North America.
- occurs in Texas, but is named for Ojo Alamo wash in New Mexico
- Alamosaurus from Texas at Big
Land Paleontology and Prehistoric
Planet interviews with Matt Wedel discuss some of the following
questions. For more information also see Titanosaur
Could sauropods rear up on their hind legs for feeding?
- Yes, they must have for reproduction, but was this a common
AMNH skeleton of Barosaurus
- Diplodocids have vertebrae with elongate neural spines for muscles
How did sauropods feed? With vertical necks like giraffes or with the
head held horizontally?
cows: From National
Geographic read about hypotheses about the long necks of sauropods.
- They could have foraged on low growing vegetation with huge horizontal
sweeps of their necks.
Computer modeling shows that Diplodocus and Apatosaurus
were ground grazers. [Stevens, K. A. and J. M. Parrish. 1999. Neck posture and feeding habits of two Jurassic sauropod dinosaurs. Science
How did sauropods pump blood to their heads if they reared up or held their
heads high to feed?
Learning estimates that large sauropds would have had to have a 400 kg
four chambered heart that could generate a systolic blood pressure of 600 mm
of Hg in order to pump blood up to the brain. Giraffes have a systolic
pressure of 300 mm of Hg.
Could dinosaurs have used their long necks as snorkels while in the water?
- Early reconstructions of sauropods show them as swamp-dwellers who spent
much of their time in the water. They were thought to be too
massive to support their weight on land and had to be buoyed up by water.
Their long necks were interpreted as snorkels. At a depth of 13 meters
an additional 0.8-0.9 atmospheres (1 atmosphere = 1.034 kg/cm2 =
pressure exerted by 10.3 m of water) of pressure would have been exerted on
its chest, 8-9 m below the surface. This probably would have kept the rib cage from expanding
enough for respiration.
Feeding in Sauropods
- Sauropods had a small number of simple teeth and did not chew their
food. Sauropods were probably constant eaters.
- Sauropods had large guts that probably housed fermentation chambers