What Is Cambrian Explosion?

The author and his colleagues specifically chose to focus on 375 million year old rocks in their search for fossils because this was the time frame that provided fish that would be useful to study from. The 385 million year old rocks provided fish that look too similar to the ones we have now and the 365 million year old rocks have fossils that don’t resemble fish. The 375 million year old rocks, however, provide fossils that show the transition between fish and land living animals.

Most Cambrian rocks contain fossils of trilobite shells, cap-shaped or flattened shells, and brachiopods (Whittington, 1985). When Walcott went looking for North American Cambrian fossils in August of 1909, he ended up in the Canadian Rocky Mountains. He and his wife found a loose block in the ridge they were searching near, split it open, and found what they later classified the “lace crab” (Briggs, 1994). Walcott knew right away what they had discovered was something different – the soft parts of the crab, such as the limbs, were preserved. During the next season, Walcott and his sons came back to the Shale, searching the slopes along the trail where they had discovered the loose block to find fossil layers. Luckily for them, the Shale rock layers were almost horizontal, and for thirty days a team quarried the ridge. The next year, they spent even longer quarrying. The last year spent quarrying the rocks was in 1917, when Walcott was 67 (Briggs, 1994). The rocks were removed from the ridge using picks, chisels, long iron bars, and small explosives. All the quarrying done by Walcott and his crew resulted in over sixty five thousand fossils, now stored in the

The author and his colleagues chose to focus on 375 million year old rocks in their search for fossils because amphibians that look dissimilar to fish were discovered in 365 million year old rocks, while fish without amphibian characteristics were discovered in 385 million year old rocks. Thus, it is possible that the evolutionary intermediary, or the “missing link” between fish and amphibians, would be discovered in 375 million year old rocks, between the two time periods. The rocks examined were sedimentary in composition, as the gradual and relatively gentle formation of sedimentary rock under conditions of mild pressure and low heat are conducive to the fossilization of animal remains. Sedimentary rock is also often formed in rivers and seas, where animals are likely to live. This site provides a resource that describes means by which fossils are formed and how the fossil record may be interpreted, and shows some examples of fossils demonstrating evolution through geological periods: http://www.fossilmuseum.net/fossilrecord.htm. In 2004, Shubin and his colleagues were looking for fossils on Ellesmere Island, in northern Canada. This location was chosen because of its lack of human development, as well as of obstructing natural formations and life forms such as trees, which

Many Early Cambrian invertebrates are known only from "small shelly fossils" - tiny plates and scales and spines and tubes and so on. Many of these were probably pieces of the skeletons of larger animals.

The effects of Ocean Acidification on the physiology of marine organisms has long been observed, as the subsequently depletion of calcium carbonate impedes the proper development of marine calcifiers. One such calcifiers, however, has exhibited considerable tolerance to alterations in seawater acidity. Indeed, through the plastic response of gene expression and modulation, the larvae of the Strongylocentrotus purpuratus, or Purple Sea Urchin, have inherited a tolerance to low pH and high temperature conditions; an adaptation which will, undeniably, prove essential for survival in this newly acidic aquatic world. This review presents the Purple Sea Urchin as a case study, to demonstrate the potential of genomic analysis to greatly augment

However, from the fossil record, approximately 545 million years ago, diversification explosives occur leading to a significant number of multi-celled complex organisms. A large number of animal groups appear suddenly, and the majority of them are still seen today and are called Phylum that is involved in the branches of the evolutionary tree ( Ogishima, et al., 2015).Because of natural selection, some animals that lack traits that are environmentally favorable are extinct and only can be traced back with the fossil record. Before Cambrian explosion, there is only unicellular organisms or simplest form of organism present, but due to change in environment factor, it has led to the appearance of a multicellular organism and exoskeleton body formed because of natural selection. Due to the shortage of oxygen available in the earth, an animal does not get sufficient oxygen for metabolic functions thus the increase in animal size is inhibited. After Cambrian explosion, water and concentration of oxygen slowly accumulated, leading to the current broad and complex animal. During Cambrian explosion the continental shelf increased, environmental diversity expanded and shallow sea produced. This phenomenon occur due to the breaking of super continental of Gondwana into smaller land masses that cause variation between animals and enable the animal to specialize. Extant species undergo a various level of evolution over time. Some species have undergone a lot of evolution however others have not evolved. For example, the giraffe has had a significant development (Doolittle, et al., 2012).The ancestor of the giraffe has a short neck. Several animals, as well as giraffe, feed on lower vegetation. With time the lower vegetation became less. With the food shortage, animals had to compete among themselves to survive, hence giraffe began to

Brachiopods were shelled animals that lived in the seas of ancient times and is commonly found in Paleozoic marine layer of the Canyon. They are made up of 2 asymmetrical shells called “valves”. One valve is longer that the other one. Bryozoans are polyp like and tiny. They form colonies that resemble corals. They form lacy structure on hard surfaces and stick structures into the water column. Crinoids resemble plant but were actually animals that looked like sea stars on a stick. They had root like structure to collect food, circulate fluid and even act like feet at times to move across ocean floor.Sponges are colony of single cells where some cells catch food with Cilia, others wander through and distribute food and some engineer the structural

Around 530 million years ago, the Cambrian explosion made a significantly fast appearance of main groups of complex organism. This was confirmed by the fossil record. Along the support by an apparent diversification of various living things, including phytoplankton, calcimicrobes and also animals. 580 million years before this, most life forms were basic, made out of individual cells occasionally sorted out into colonies. The Cambrian explosion can be said to happen in waves. The initial, a co-evolutionary transformative ascent in differing qualities as animals investigated specialties on the Ediacaran ocean bottom, trailed by a second development in the early Cambrian as they established in the waters column. The pace of advancement found in the Cambrian times of the explosion is not paralleled amongst the marine creatures: it changed all metazoan clades where Cambrian fossils were found. Later radiations, the fish in the Silurian and Devonian era, included less taxa, for the most part with basically the same body plans. Despite

There are about thirty modern animal phyla, including chordates, arthropods, annelids, corals, sponges, mollusks and echinoderms. All of which trace back to the Cambrian time period, 530 to 525 million years ago.

The formation of Earth, 4.5 billion years ago till the evolution of hard-shelled animals, about 500 million years ago, is called the Precambrian period. There are many events during this time that are specific and affect the Precambrian life. The earth was formed and the first tectonic plate arose and began to move which caused many variations on the earth conditions during Precambrian that affected atmospheric composition and oceans. The level of oxygen arose in the atmosphere which enabled the enrichment of atmosphere with oxygen reaching its peak about 600 million years ago which enabled the first appearance of animal life that required oxygen for the production of collagen and the formation of skeleton. Also, during this period the ozone

The process of diagenesis encodes information regarding the physical and chemical processes operating in nature, which precedes the taphonomical journey of a bone into the lithosphere. When decoded, a fossil or an archaeological bone entails a series of natural processes of modification that perhaps decided the ‘destiny’ of a bone to transform into a fossil over the years of its residence into the sedimentary environment. Understanding these processes involved in the bone diagenesis is crucial to the reconstruction of ecological settings of an area(cite the papers on bone diagenesis and process of fossilization e.g. papers in “Archaeometry 2002 issue on bone diagenesis and also the proceesings of the Conference on “Bone Diagenesis” held

The fossils of Trilobite are very common is certain rocks. This is most likely due to the fact that many of them lived on the sea floor where fossilisation in low energy environments takes place. As a result of these trilobites being so common, they have been a main focus point for the study of both microevolution and macroevolution in the fossil record (Barnett, 2014).

Even though anoxia is in general reflected on as an essential pre-requisite, “anoxia alone is not sufficient enough to account for Burgess shale-type preservation,” (Garson 2012). Furthermore, the necessity of anoxia is not universally agreed upon (Garson 2012). Yet, while rare and commonly absent from today’s fossil record, this type of preservation is very common throughout most Burgess shale-type deposits of these ancient fossils (Gaines 2012). Localities of these types are somewhat confined to Series 2 and 3 of the Cambrian (Garson 2012).

This example continues to explain that the fossils found at the top of the geological column are descendants of those found at the bottom of the column because of the change in geological structure and the life forms present in each layer (McMullen et al., 2014). Another example of this stratification includes the Lewis overthrust which provides fossils evidence in this order from the mid-Tertiary to early Miocene epoch (Hewett, 1920). The gradual change of organisms can be found in the form of transitional fossils. Transitional fossil are examples of organisms which change from a distinct anatomical class of organisms to another different anatomical class of organism an example of this would be Archaeopteryx(Xu et al. , 2011). Archaeopteryx is an example of a transition of the early avian reptiles to modern winged and feathered birds (Xu et al., 2011).Another example of a transitional fossil is Tiktaalik which is was a fish-like animal which possessed tetrapod anatomy such as early walking limbs and jaw structures, it can be seen as a good example of the transition from fish to early land tetrapods.

The time between the formation of the earth and the beginning of the Cambrian(about 570mya) is a 4000 my long period known as the Precambrian, this includes approximately 90% of geological time of which we know very little about as pre-Cambrian rocks are poorly exposed, many have been eroded or metamorphosed and fossils are seldom found.