What were some Jurassic period sauropods?
The following lists the most prominent Jurassic period sauropods and some of their characteristics:
Diplodocus: This dinosaur gives this group its name; it was 89 feet (27 meters) in length, with an estimated weight of 11 to 12 tons (10 to 11 metric tons).
Apatosaurus: Once commonly known as Brontosaurus, it was shorter and stockier than the Diplodocus; it was also one of the largest land animals that ever existed, measuring over 75 feet (23 meters).
Barosaurus: Similar to Diplodocus, but its cervical vertebrae were 33 percent longer.
The Diplodocus was nearly 90 feet (27 meters) long, weighing in at over 10 tons (9 metric tons), and was one of the largest sauropods to roam Earth (iStock).
Suuwassea: Found in the Morrison formation of the United States, it measured about 46 to 49 feet (14 to 15 meters) in length.
Supersaurus: Another candidate for the longest dinosaur; it is estimated to have been about 108 to 112 feet (33 to 34 meters) long.
Brachiosaurus: This dinosaur gives its name to the group; the largest found fossil of this late Jurassic dinosaur was approximately 82 feet (25 meters) long and 42 feet (13 meters) high, about the height of a four-story building.
Lusotitan: This dinosaur had long forearms; it also averaged about 82 feet (25 meters) long. The most complete fossil found in Portugal did not have a skull, but scientists still believe it was a member of the Brachiosauridae.
Camarasaurus: A relatively small sauropod; it was approximately 60 feet (18 meters) long; its forelimbs were not as proportionally long as the brachiosaurids.
What were some general characteristics of the other saurischian group, the theropods?
The theropods (Theropoda) had many general characteristics. Because they were carnivores, their teeth tended to be blade-like, with serrated ridges. Their claws, especially on the hands, were often recurved and tapered to sharp points. The outer fingers of the hand were either reduced in size or were completely lost. Most theropods were long-legged, bipedal, slender, and quick all characteristics that enabled the animals to more easily catch their prey. They also had three walking toes on the hind feet.
Theropods had hollow limb bones; some went one step further and had air-filled (pneumatic) bones in certain parts of their body. For example, in some dinosaurs, pneumatic bones were found in the middle of the tail; in others, the air-filled bones were present at the back of the skull.
There is a good deal of evidence that larger theropods attacked other animals. For example, sauropod bones found in Colorado show the bite marks from a large theropod and sometimes the bones indicate that the prey survived the attack. At other sites, trackways show the footprints of theropods chasing or stalking smaller sauropods.
In general, what characteristics determine if a dinosaur skeleton is that of a theropod?
There are many unique skeletal characteristics paleontologists use to determine if certain dinosaur bones belong to a theropod. In general, here are a few of the characteristics:
1. The bone in front of the eye (lacrimal) extends onto the top of the skull.
2. The lower jaw has an extra joint.
3. The shoulder blade (scapula) is strap-like.
4. The upper arm bone (humerus) is less than half the length of the upper leg bone (femur).
5. The elongated hand has lost (or has shrunken) two outer fingers.
6. The top of the bones in the palm of the hand (metacarpals) has pits where ligaments were attached.
7. The fingers have elongated bones between the second-to-last and last joints.
8. Near the head of the upper leg bone (femur) is a shelf-like ridge for the attachment of muscles.