Lecture 12: Sauropodomorpha Flashcards
Define saurischia
The “lizard-hipped” dinosaurs in most, the pubis projects forward and downward as is primitive for reptiles, Named by H.G. Seeley in 1887, includes the smallest and the largest dinosaurs, all of the carnivorous dinosaurs, plus more herbivores
Derived features of saurischia
Subnarial foramen- opening beneath the nostril area
Elongation of the rearward neck vertebrae (resulting in longer neck)
Increased articulations between vertebrae
Robust thumb supported by a broad metacarpal bone
digit II of hand longer than digit III
Eoraptor
Small (~1.3m long) bipedal early saurischian from the late triassic of Argentina, intially described in the 1990s as an early theropod. Reinterpreted in the 2010s as a sauropodomorph and shares with other sauropodomorphs skull features to herbivory, thumb claw rotated forward
Sauropodomorpha
Sauro-lizard, pod-foot, morpha-foot (feet retained all five digits, as in lizards) Includes all of the biggest dinosaurs Weight up to: 75,000 kg Length: up to 40m Height up to 6m at the shoulder
Survival over 160 million years
Animals of that size test processes such as: Weight support neural circuitry Respiration digestion
Prosauropods
Evolutionary radiation in the last triassic, thriving with worldwide distribution in the early jurassic, including Canada (Nova scotia) and even antarctica, extinct in the middle jurassic. probably not a monophyletic group; some were more closely related to sauropods. Small heads, long necks and bulky bodies but most were bipedal, generally smaller than sauropods, the first tall browsing herbivores in Earth’s history
_______: a typical prosauropod
Plateosaurus, bonebeds suggest herd living
Sauropoda
monophyletic, shortening of the rear portion of skull, lower temporal opening situated partly beneath eye socket, 12-19 neck vertebrae and 4-7 sacral vertebrae, quadrupedal. Massive and vertical limbs and solid long bones. Broad snout with spoon shaped or pencil like teeth at the front of the jaw, loss of overbite, long tail (modified in some species to end in a small club or a very long whip)
What did sauropoda evolve from?
Prosauropods in the late triassic, Increased in size and diversity in the jurassic, absent in north america in the late cretaceous but succesful until the end of the cretaceous in most of the world
History of discovery
First sauropodomorph species were named from European discoveries in the 1830s and 1840s: thecodontosaurus, plateosaurus.
However, they were NOT among the reptiles included by Richard Owen in his original concept of dinosauria
Sauropods and prosauropods not formally classified together as sauropdomorpha until 1930s
North American Discoveries
New chapter in sauropod research began in 1870s by cope and Marsh. Most prolific source is the Morrison formation, late jurassic, western USA. continues with new sauropods from this formation still recently being named Suuwassea (2004) , kaatedocus (2013). NO sauropod body fossils yet from Canada, but footprints recently found in BC
Camarasaurus
Most common sauropod in North America, 18m long body, head high, short and powerful, teeth not restricted to front jaws
Diplodocus
27m long, nostril opening far back on skull, elongate snout, pencil-like teeth at the front jaws only, long drawn out tail with 80 vertebrae acting as whip
Neck vertebrae in _________ with Y shaped neural arches
holding a ligament called nuchal ligament
Diplodocus
Seismosaurus
named in the early 1990s, may be a very large individual of diplodocus
Sauropods worldwide
Tendaguru hills in Tanzania, Major expedition by E. Fraas and Werner Janensch, 1907 500 local workers
size of expedition
225000 man days, over 100 articulated skeletons, hundreds of isolated bones, 4300 jackets to be carried to port city, 5400 walks each one four days, specimens shipped to Berlin, new late jurassic sauropods
Giraffatitan=
one of the tallest sauropods, on display in Berlin from Tendaguru
Rebbachisaurids=
Bizarre early late cretaceous diplocoids of South America , Africa and Europe: most are recently discovered
Nigersaurus is specialized for
low feeding with dental battery at the front of the snout (not seen in typical sauropods) but skull is extremely lightly built. Highest rate of tooth replacement for dinosaurs: individual teeth lasted as short as two weeks
Titanosauria
Very succesful clade, the only sauropods at the end of the late cretaceous. wide heavy bodies, more flexbile vertebral articulations, some of them had osteoderms. Huge range of body size: some titanosaurs were relatively small sauropods, others were among the largest that ever lived
Yonginglong, a titanosaur from the early cretaceous of ______ published in early 2014, one of many recent sauropod discoveries
China
Taphonomy
Most skeletons are incomplete: bodies too big to be rapidly buried, most skulls are missing, some late cretaceous monoglian sauropods are known only from their skulls (nemegtosaurus)
Habitats
Wide geographic distribution, different habitats (fine grained floodplains, channels, eolian sandstones, lakes, rivers. Many represented in the morrison formation, jurassic of western USA
