SAUROPODS
Sauropoda (also called Sauropods) are categorized under the saurischian and are lizard-hipped dinosaurs. O.C. Marsh coined the term ‘sauropoda’ in the year of 1878. This term is also derived from the Greek meaning, “lizard-foot”. Sauropods are known for some of their massive body sizes and contain some of the largest dinosaurs that have ever lived on land. Some well-known groups include the Diplodocus, Apatosaurus (or Brontosaurus), and Brachiosaurus. It is believed that sauropods reached heights of around eighteen meters or sixty feet; lengths of around thirty-four meters or one-hundred and ten feet; and weights of approximately one-hundred metric tons. These species usually had long necks and tails, small heads, and thick pillar-like legs. They also were herbivorous (plant-eating) animals. They are one of the most long-lived dinosaur groups and have existed for around one-hundred million years, spanning from the Late Triassic period to the Late Cretaceous period. Sauropods entered the scene during the Late Triassic period where they resembled the closely related group of the Prosauropoda. They also became more geographically widespread and diverse during the Late Jurassic period. This group of dinosaurs possibly contained at least one-hundred and twenty. As a result some of their bold features, Sauropods have become a popular dinosaur group.
SIZE
The body design of sauropods was not as diverse as other dinosaurs (as a result of their huge body size) but did have notable variety. Sauropods were enormous creatures. They could reach heights up to eighteen meters (sixty feet), an example would be the Sauroposeidon; lengths of around thirty-four meters (one-hundred and ten feet), such as the Supersaurus; and could weigh up to one-hundred tons, like the Argentinosaurus. Even the smaller sauropods such as the Europasaurus (five to six meters long or twenty feet) were considered the largest in their ecological community. During their juvenile years, sauropods grew rather quickly; as a result of this, their size alone became a defense against predators. They also ate a lot; they ate hundreds of pounds of plants and leaves daily. This type of eating helped them maintain their size. However, due to their large sizes, their movement was restricted.
NECK
Sauropods also had long necks. Some sauropods, such as the Mamenchisaurus, had necks that could reach up to forty-six feet (fourteen meters) in length. Sauropods could even grow their necks up to four times the length of their backs. However in some instances, this was not the case, such as for the diplodocoid sauropod, Brachytrachelopan, whose neck was shorter than its backbone. The ways in which sauropods positioned their necks varied within the group. Sauropods within the Brachiosaurid group for example, positioned their necks vertically, which possibly allowed them to get leaves from trees of high length. Sauropods such as the Diplodocids positioned their necks horizontally, which possibly allowed them to poke into forests and receive foliage that; otherwise, they would not be able to because of their huge sizes. They also had extra cervical vertebrae that allowed them to position their bones in an efficient way. As a result of their long necks, sauropods had access to a wide range of foliage which allowed them to eat large amounts of vegetation without expending much energy by moving from tree to tree.
SKULL/TEETH
Sauropods had hollowed vertebrae and small heads (and small brains); these features are convenient to the sauropod body plan because they reduce the pressure placed on the neck. Their skull had enlarged eye-orbits. Their nostrils were located within the upper region of their skull as opposed to the end of the snout. Sauropods obtained a certain set of teeth depending on what types of plants they ate. Their teeth were either flat and spoon-shaped like the Camarasaurus and Brachiosaurus or thin and peg-like like the Diplodocus. Sauropods with peg-like teeth used their teeth to strip leaves off of trees but did not use them to chew. Sauropods also had large stones in their stomachs (gastroliths) that could help digest the leaf matter. Sauropods that had spoon-shaped teeth could have possibly used their teeth to eat tougher foliage that depended on more effective methods of grinding and chewing. Sauropods’ teeth were also restricted to the front portion of their mouth, which made chewing difficult.
TAIL
Sauropods tended to possess long tapering tails. An example of sauropods with wipe-like long tails is the Diplodocus. Their tails could have reached lengths of about forty-five feet long (fourteen meters). These tails could have counterbalanced their long necks. Sauropods could have used their tails as whips as a means to defend themselves. They could have also possibly waved their tails to create sonic booms to intimidate their predators. Another use of their tails could have been to communicate with other sauropods as well as potential mates.
ABDOMEN/ AIR SACS
Sauropods had large bodies that encompassed a large stomach. They were able to scarf down massive amounts of vegetation because it is said that they had gastrolith stones in their stomachs that may have helped them digest the plants they were consuming. This was helpful because they could not chew as efficiently (chewing would actually limit their size because it would take more of their energy) because of how their teeth were composed. It is hypothesized that sauropods swallowed stones that gathered in the gizzard area of their stomach to form a ‘grinding mill’ to digest the food consumed. Another hypothesis (rejecting the previous hypothesis) to their digestive system is that obtained symbiotic microbes that helped in the process of breaking down cellulose in the cell wall of the plants. The enormous size of the sauropods may have even allowed the retention of food in the digestive system for long periods of time. Sauropods also obtained a system of air sacs. These air sacs may have helped the evolution of long necks in some sauropod groups by taking up respiratory unused space and reducing mass. These air sacs may have also given sauropods respiratory and thermoregulatory advantages.
LIMBS
Saurpods were quadrupeds (because of their large size) and had four column-like legs. Their limbs were positioned directly below their body. Sauropod pelvis and limbs obtained sacral vertebrae and leg bones that interlocked and resembled pillars. This configuration created a sturdy foundation to support that size of sauropods. Their hind-legs were thick and strong and included club-like feet comprised of five digits, with the inner three toes having claws. Their fore-legs were slender than their hind-legs and obtained roughly tubular figure fore-feet, with the first digit having a claw. Their fore-feet were also built for supporting weight.
ARMOR
Although their enormous size and whip-like tails could have deterred predators, some groups of sauropods had body armor in addition. The Agustina, Shunosaurus, titanosaurses such as the Saltasaurus and Ampelosaurus would be examples of sauropods with body armor. The Agustina formed spined backs; the Shunosaurus had small clubs on their tails, maybe as a source of defense, and titanosauruses such as the Saltasaurus and Ampelosaurus developed bony scales that covered portions of their body, maybe to protect against bites or claw scratches.
FOSSILS
The remains of sauropods can be in the form of bones or footprints. Fossil remains of sauropods have been discovered on every continent. The fossil remains of sauropod footprints show that they migrated in herds.
REFERENCES
Dinosaur Facts. [ONLINE] Available at: http://www.sciencekids.co.nz/sciencefacts/dinosaurs/sauropodstitanosaurs.html.
Pillai (2012). Fins to feet: A history of vertebrate life on earth. [ONLINE] Available at: http://finstofeet.com/2012/05/13/sauropods-whale-lizards/.
Sauropod dinosaurs. [ONLINE] Available at: http://www.bbc.co.uk/nature/life/Sauropoda.
Sherwin and Thomas. What the Fossils Really Say about Sauropod Dinosaurs. [ONLINE] Available at: http://www.icr.org/article/6418/.
Taylor et al. (2013) Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36http://dx.doi.org/10.7717/peerj.36
The Sauropod Dinosaurs. [ONLINE] Available at: http://www.ucmp.berkeley.edu/diapsids/saurischia/sauropoda.html.
What are Sauropods?. [ONLINE] Available at: http://www.wisegeek.com/what-are-sauropods.htm.
Pillai (2012). Fins to feet: A history of vertebrate life on earth. [ONLINE] Available at: http://finstofeet.com/2012/05/13/sauropods-whale-lizards/.
Sauropod dinosaurs. [ONLINE] Available at: http://www.bbc.co.uk/nature/life/Sauropoda.
Sherwin and Thomas. What the Fossils Really Say about Sauropod Dinosaurs. [ONLINE] Available at: http://www.icr.org/article/6418/.
Taylor et al. (2013) Why sauropods had long necks; and why giraffes have short necks. PeerJ 1:e36http://dx.doi.org/10.7717/peerj.36
The Sauropod Dinosaurs. [ONLINE] Available at: http://www.ucmp.berkeley.edu/diapsids/saurischia/sauropoda.html.
What are Sauropods?. [ONLINE] Available at: http://www.wisegeek.com/what-are-sauropods.htm.