Chapter 6 Saurischia Lizard Hipped Dinosaurs These dinosaurs are the first ones we re looking at on the right side of the cladogram The saurischians include the long necked sauropodomorphs the largest animals ever to walk on land tiny meat eaters the size of pigeons and the mighty T rex The distinguishing feature of all saurischians dinosaurs are o a pubis that points forward like that of a lizard o a long neck at least 1 3rd of the length of spinal column to hip The distinguishing features of the sauropodomorphs in particular are o Extremely elongated necks 10 or more vertebrae o Enlarged thumb claws DON T NEED TO KNOW THIS o Prosauropods early Sauropodomorphs Medium sized herbivores 10 25 feet long with jaw joints below the tooth row like ornithischians the ornithischians were also plant eaters Their leaf shaped teeth don t occlude they cropped plants They had gizzard stones to grind up the plants once ingested In doing this they polished the rocks very well Prosauropods clearly had the ability to stand on their hind legs Nevertheless their trackways show that they mainly walked on all fours except when they saw a tree and got up to eat it or stood up to survey their surroundings and often in large groups True Sauropods the earth shakers These were the large to giant long necked herbivores of the Mesozoic era The distinguishing feature of the Sauropods was nostrils located atop their heads No one seems to know why their nostrils were located here These animals were elephant sized or bigger Their bones are an absolute pain to dig up it takes a long time 8 days for one bone but they have 350 bones They are usually found incomplete and headless because the heads were so delicate and washed away before they could be fossilized o Actually the whole dinosaur was delicate although this was especially true in the neck area o Because of their long extremely large necks and tails the vertebrae were very lightly built often with air sacs like those of bird bones There is much debate as to how many dinosaurs are in the Sauropodomorph group o Diplodocids the longest dinosaurs They had low skulls and pencil shaped teeth Supersaurus and Seismosaursus are giant diplodocids but they are known only from a few bones They may have been 140 feet plus long Test question you cannot fit one of the Supersaurus or Seismosaurus of them in the classroom Ruby Diamond Auditorium but you could just barely fit one of them in the building if you start at the stage and go to the front steps inside Wescott Mamenchosaurus Had an amazing thirty three foot long neck In the late 1800s a giant vertebrae from an animal called Amphicoelias was found Perhaps the largest dinosaur ever found Somehow the bone from it has been lost The most famous diplodocid was Apatosaurus also known as Brontosaurus Marsh found it in 1877 and named it Apatosaurus He found another and thought it was different and named it Brontosaurus The record was set straight in the 1970s all of them are technically called Apatosaurus now When Marsh found the Brontosaurus it had no head He had an extra head from the Camarosaurus so he slapped one of those on instead In 1916 Holland found one with the correct head and tried to mount the Carnegie specimen with it AMNH big shot Osborn strong armed him into not doing it It went headless for twenty years Holland died and they put on the Camarosaur head anyway Some people think the diplodocids reared up on their hind legs to feed others think they just grazed normally The AMNH Barosaur was mounted upright popping a wheelie Caused a lot of controversy some people said it would pass out if it did this because its heart was so far away from its brain This led to a strange paper in Lancet saying that they had six Finally someone said they would have had to elevate themselves This led to another bizarre theory that mating only occurred in auxiliary hearts to mate water please Who knows Really no one does The tallest dinosaur Sauroposeidon 56 feet Would not fit in the classroom Ruby Diamond Auditorium Cetiosaurs whale lizards Titanosaurs the last of the Sauropods One type Titanosaurs even crossed the Isthmus of Panama only to be eaten by the T rex Another Saltosaurus had armor like the ankylosaurs When Richard Owen first looked at the remains of the sauropod Catiosaurus he thought it was a giant sprawling aquatic crocodile It was later determined that it had walked upright because it would have had to walk in a rut to walk in a sprawling manner since its stomach would have been so big These animals were not aquatic either from footprint evidence we now realize that they walked on dry land a lot and had feet like those of elephants who do not do well in wet environments Furthermore physiological studies show they could not have inhaled air down their trachea if they were that far underwater We now think that they fed on land on tall trees this may be why Sequoia trees are so tall they showed up at around the same time at these animals Since there is a limit to how big an egg can be about ten pounds Robert Baker said that these animals probably had large live young like elephants how else could they have gotten so big We have since found their eggs which are surprisingly small and volleyball sized These animals had small babies that just grew really quickly Curiously sauropod eggs are often but not always laid in a line laying on the run for thirty or forty feet We know from trackways sometimes numbering in the millions that these animals traveled in great herds It appears that the young were protected in the middle Holes in the ground in Utah have been proven to be dinosaur tracks this is called bioturbation One trackway appears to show an allosaur and a sauropod intereacting possibly an attack iClicker question Why is the Oviraptor named the egg stealer It was originally found on top of a nest thought to belong to Protoceratops
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