Trilobites
Trilobites are extinct sea creatures that were one of the first forms of life on earth.
They ruled the world before the time of the dinosaurs, from the Cambrian Period to the
Permian Period (between 245 and 600 million years ago). Trilobites are the only extinct
form of Arthropods (invertebrate animals having jointed bodies and legs),and were related
to the lobster and crab. Their closest living relative today is the horseshoe crab.The name
Trilobite refers to it's three lobes, or body sections, consisting of a central axial lobe, and
two pleural lobes on the sides. The three main parts of it's body are called the
Cephalon,(head) the Thorax (body), and the Pygidium (tail). There are 8 Main Orders of
trilobites, and over 15,000 different species, many of which have a stratigraphic value,
especially those found within Cambrian and Ordovician rocks. It is the fact that trilobites
are found world wide which makes some of them serve as excellent index fossils, and it is
their short life periods which allows precise dates and correlation’s to be made about the
rocks in which they are found.
Most trilobites were sea floor dwellers, living in the soft sediments, while others
were free swimming. They appear to have been exclusively marine organisms since the
fossilized remains of trilobites are always found in rock containing fossils of other
salt-water animals, e.g. brachiopods, crinoids, and corals. Trilobites ranged in size from
1/4 of an inch,and smaller, to almost 3 feet long. Trilobites were also the first creatures to
develop eyes and sensory organs. Trilobites had two compound eyes. In some trilobites,
the eyes had densely packed lenses and may have served merely as a light sensitive
warning...
... middle of paper ...
...ve found them a
good source of food. The Trilobites fought back for a time, growing spines during the
Devonian period but these were no match for the larger predators.
The fossilized remains of trilobites are useful because they help scientists develop
relative time scales for the ancient marine environment. Because trilobites evolved quickly
and were widely distributed, comparing the trilobite fossils found in rock layers in different
regions of the earth can indicate which rock layer is older than the other. Trilobite fossils
are particularly helpful in developing time scales for the early Paleozoic era. Trilobites
were highly successful bottom dwelling sea organisms with over 10,000 species. They
thrived for 300 million years as the most abundant and successful ocean animal through
the Cambrian period until they bit the cosmic dust in the Permian era.
Paleontologist L.B. Tarlo said that it was very difficult to ascertain the length of Liopleurodon. This was so because no complete skeleton was found. He then predicted from the skull, the skull was approximately one-seventh of the total length of the body. When we apply this ratio to the largest skull specimen of L. ferox, the total length of the body comes out to be a little more than 10 meters. The normal size from this calculation would be around 5-7 meters in length. The weight of it was estimated to be around between 75 to 150 tons. The more recent study and the finding of the complete skull of Liopleurodon. It showed the total size of the body was actually five times more the length of the skull. Thus, reducing the expected body size of it furthermore. The maximum size that a L. ferox could reach is just up to 6.4
The braine is part of three divided that represent front, back and saggital planes which divides the left from right of braine. A horisontal planes divides the braine in to top and bottom position.
...however, with further research, it came to light that this was not just a “unique species” but an entire phyla that was new to science (Adler 2013). Why a new phyla? “What made the creatures seem new is they have no living descendants. They represent entire lineages, major branches on the tree of life, left behind by evolution…” (Adler 2013). While other lineages did survive-actually a collateral predecessor of the vertebrates, and that means us! (Adler 2013).
Sure, you can imagine a crab sitting on the bottom of the ocean, but if you came across a pill bug you probably wouldn't scream, 'Check out that crustacean!', but pill bugs are crustaceans that live on land! There are too many groups to mention here, so let's just highlight a few, starting with Copepods, which are extremely small crustaceans. There are over 13,000 species that are considered Copepods. Some inhabit freshwater, some live in saltwater, others live in moss and some are even parasitic. The Copepod's claim to fame is probably their importance in the food
The cerebrum consists of two hemispheres, separated by a deep fissure called the Corpus Callosum, the hemispheres are divided into four lobes; the frontal, partials, occipital and temporal.
Shubin, N.H., & Marshall, C.R. 2000. Fossils, genes and the origin of novelty. Paleobiology, 26(4): 324-340.
Fossil preservation has always been the most accurate way to determine what species lived during a specific time period. Through correlations and radiometric dating, time periods have become more accurate and being able to tell what lived during those times became possible. Although conditions have to be correct for fossilization, Pleistocene fossils are widespread and often well preserved. In the La Brea tar pits of present day Los Angeles, hundreds of thousands of preserved bones have been found that give a good idea of the animals that were present during this time. Many of the animals preserved are animals that can still be found today and would be found in the Los Angeles area if not for urbanization. Animals that were present during this time include camels, mammoths, and saber-toothed cats among others (Harris and Jefferson, 1985). Below is a picture of a saber-tooth fossil found in the La Brea tar pits.
Display, communication, and the act of mating are estimated behaviors involved in the mating process of dinosaurs. The sexual behaviors of modern vertebrae are often used as a starting point to estimate that of dinosaurs. For instance, most modern vertebrae go through a sexual selection process as they choose their mate based on preferred traits. This is demonstrated with the modern day peacock. The visual stimulus the male provides with its tail feathers aids in the opposite gender’s sexual selection process. According to Martin, in this respect, the ceratopsians have the most obvious sexual displays in the form of ornate and broad head shields with horns, knobs, and bosses. Though these body parts could definitely prove useful to fend off potential predators, it is more likely that they were used for: visual recognition within their species; pote...
For the first known citing of one of these creatures, you would have to go back to November of 1861, when crew members of the French dispatch steamer Alecton spotted what appeared to be a large sea monster off the coast of the Canary Islands. The crew threw harpoons at the creature, but those would not stay in the flesh for long. When the crew got close enough to put a noose around the creature, the rope tightened and cut through the animal, causing most of it to sink to the bottom of the sea. The crew, however, managed to pull the tail of the creature on board, and bring it back to the French Consul. From there the tail and a report about the creature made its way to the French Academy of Sciences.
Han, J., Zhang, Z. F., & Liu, J. N. (2008). A preliminary note on the dispersal of the Cambrian Burgess Shale-type faunas. Gondwana Research, (1), 269-276. doi:10.1016/j.gr.2007.09.001
Paleogeologist knows a fossilization process only begins when an organism dies and immediately covers with mud or silt before it gets ruined by scavengers. After being covered under earth’s surface, minerals in the water replace the minerals in the organism’s tissues, and bones are the most common tissues for mineral replacements. Because the soft parts of the body usually decays and left with the hardest parts to be buried. After much time has passed the body of the organism will slowly turn into a sedimentary rock. This process would sometimes take up to millions of years; therefore fossils do not form easily.
Now for our eyes we use them for vision, their like our own personal camera’s,
Diplopoda is a class, belonging to the subphylum of Arthropoda Myriapoda, consisting of about 10 000 species of animals which have two pairs of legs for each body segment and are often known as Millipedes. Hence the name, they do not have one thousand legs.
Radiocarbon dating is used to tell how old something is. When some normal carbon gets hit by the rays of the sun, it turns into carbon 14. Plants absorb this radioactive carbon in the form of carbon dioxide. Animals receive this carbon from eating the plants. When the organism is dead it loses the carbon 14.