Introduction
Dinosaurs can be described as reptiles but more specifically are of the clade Dinosauria group. History suggests that they initially appeared during the Triassic era, that is more than two hundred million years ago. They gained dominance as terrestrial vertebrates after the extinction that occurred two hundred million years ago which continued throughout the Cretaceous and Jurassic periods. The fossil record reveals that birds are the modern and feathered version of dinosaurs that evolved from past theropods in the Late Jurassic age. They are the only ones in the lineage to survive the extinction event about sixty-six million years ago. Therefore, a dinosaur can be divided into avian and non-avian, the latter being extinct.
While a dinosaur was ancestrally bipedal, many extinct groups included species that were quadrupedal and others could shift between the stances. Ornate display features such as a horn or crest, are common to every group and extinct categories developed skeletal alterations, for example, spines and bony armor. Whereas the modern times surviving avian lineage are small in general due to constraints of flying, many prehistoric dinosaurs were huge. The largest are approximated to have attained lengths of one hundred and thirty feet and heights of fifty-nine feet. Considering every other animal, it is safe to state that they were the largest ever.
The misinformation that non-avian dinosaurs were generally gigantic is founded partly on the preservation bias, as huge, sturdy bones are most probably to last till they are fossilized. Many of them were rather small and measured about twenty inches in length. The first fossil of the animal was identified in the early nineteenth-century. Since that time, mounted fossil skeletons have become a great attraction at museum in the entire world and the animals an enduring component of popular culture. The main aim of this paper is to look at the methods of finding, excavation, preservation and identifying fossils.
Finding
Majority of the ancient animals never reached a point of becoming a fossil. The carcasses after dying were probably consumed by organisms or worn away by water or wind. However, there are times that the conditions were suitable and the remains were preserved. The most common procedure of fossilization occurs when an animal is buried by sediment such as silt or sand shortly after death. The layers of sediment protect the bones from rotting (Bakker 60). As decomposition continues, every fleshy part wears away and only the hard structures, for example, horns and teeth, remain.
In a period of millions of years, water in the surrounding rocks encompasses the hard components and minerals in it replace them. When the latter completely substitute the organic tissue, what is left is a solid rock copy of the actual specimen. A fossil is found nearly exclusively in sedimentary rocks which are those that exist when silt, sand, organic material and mud settle out of air or water to create layers compacted into a rock. Thus, when searching for non-avian dinosaurs particularly, a paleontologist looks for outcrops of sedimentary rocks that formed in the Mesozoic age. This refers to the period that these animals existed (Bakker 62). The scientist will search in areas with less vegetation on the surface of the land. The reason for this is to ensure that fossil particulars weathering out of the rock layers are visible.
The areas of barren ridges as well as ravines are usually described as badlands. To find proper Mesozoic, sedimentary rock layers, a paleontologist uses geologic maps which reveal the type of layers of various geologic times that are exposed on the surface. Once they are discovered, the search begins with a reasonable hope of finding the animals they are targeting. During this process, other fossil types are serendipitously found (Bakker 65). The scientist may as well carry out expeditions to different parts of the world where there is more chance of finding a fossil.
In order to succeed, the fieldwork needs much funding as well as thorough planning. All trips are designed to attempt and discover fossils that will reveal new details on specific research questions. Scientists usually opt for destinations for their field work in areas whereby the animal remains have already been discovered before. If not, satellite images and geologic maps are utilized to spot places where rocks of the right age as well as ancient surroundings are exposed on the surface.
The paleontologist can also begin by conducting prospecting which involves hiking slowly across ridges and through ravines while monitoring the ground in hopes of finding fragments weathering out on the surface. This procedure most times covers five to ten miles daily (Farlow et al. 450). Once a fragment is found, the collector polishes away the loose matter on the surface to check whether more of the specimen is buried. If this is the case, quarrying is started to gather the fossil.
First, rock hammers, awls, chisels as well as other tools are utilized to eliminate the rock covering the fossil to see how much skeleton is present. After exposure of the bones, special glue is used to aid in holding the fossil together by applying on the fractures and cracks. Next, a trench is mined around the area so that it sits on a low pedestal, still encased in its surrounding rock or matrix. A covering of damp toilet paper is put on top of the matter prior to the wrapping around the matrix with a layer of plaster bandages to form a hard cast. After hardening, the excavation process begins.
Excavating
The process of excavation involves five steps including prospecting, excavating, mapping the dig site, making plaster jacket and packing. In the initial step, a scientist looks for fossils in desert regions whereby there are sedimentary rocks rather than igneous or metamorphic ones. The main rule for establishing where to search is geologic era. In case one knows the age of a rock in a place, they can start to search for animals that existed at that particular time. A geological map is used to aid in achieving that. During an expedition, the team members split up so that they are able to cover more ground. The objective is to investigate an extended area where a fossil may be discovered to locate sites where it may be worth digging.
The next step is excavating which can take a duration of days to weeks or even several field seasons. This is dependent on the hardness of the rock and how much overburden exists. In 2012, when component of a new species of oviraptorosaur was uncovered, it took the team of scientists several days of jackhammering to eliminate the matrix on top and one week to excavate (Bakker 70). There are many pieces of equipment as well involved in this process. They include rock hammers, pickaxes, whisk brooms, chisels, shovels and trowels. In the event that there is much rock above a fossil, a gas jackhammer is used to release the overburden.
The third step involves mapping the digging site which happens once more of the fossil is uncovered and there is a sense of the outline. The individuals responsible lay out a grid over the specimen and draw every visible bone on a paper with the description and number of all pieces. The objective is being able to document the initial position of the bones when they were found. The next step after that is making plaster jackets (Farlow et al. 455). To create one that holds together the fossil and protects during transportation, a trench is first dug around the specimen to form a mushroom-like island with a moat surrounding it.
Afterward, the scientists cover the surface using a separator, often toilet paper or paper towels to prevent sticking of the plaster from the specimens. They then make mud with fine-grained matrix and water, and fill all the gaps until the specimen’s surface is smooth. It thus becomes easier to remove the field jacket during the opening part in the laboratory. A plaster is added, completely covering the island cap to form a partial field jacket. After digging deep and undercutting the jacket, they can flip it over and remove it from the ground.
Due to the fact that the quantity of earth, plaster, rocks and fossil can result in much weight, the jacket can be reduced or excess matrix removed from the underside until the bones become visible. Then that side is capped with plaster to form a completely covered plaster jacket. Lastly, they have to wait sometime until the plaster dries. Water adds much excessive weight to the plaster and that is the reason they need it to dry as much as possible before attempting to pick it up.
The last step is packing all the materials and heading to a laboratory. If the team working on the jacket is small, the scientists have to strategize early on how to transport the jacketed fossil. o, the work is done in hilly and rocky places where it is near impossible to get trucks closer to a site. Once the fossil is taken back to the field museum, it ultimately goes to one of the labs for preparation.
Preservation
An individual who prepares fossils is highly skilled technician who extracts from the surround matrix, uses consolidants and adhesives to stabilize them and prepare casts and molds of the specimens. When a fossil arrives from the field, it is encased in plaster jackets, and the rock or matrix which surrounds it. Preparation involves cutting open the jacket as well as eliminating the matrix covering the fossil.
The matrix may appear crumbly and soft when the mud or sand is poorly cemented together or it can seem hard when proper cementing has been applied on the sediments. A wide range of tools are needed to eliminate the matrix and make the fossil stable. Commonly, dental apparatus is utilized to thoroughly pick away sediment near the bone along with customized needles made of carbide steel.
In the past, hammers and chisels were utilized to eliminate blocks of matrix farther away from the bone. However, recently, smaller pieces of mechanical apparatus have replaced them. They include miniature jackhammer named air scribe, small grinding wheel and tiny sand-blaster powered by compressed air. Individuals who are responsible for preparing fossils usually use the tools during assessment through a precision microscope under high-quality lighting to ensure delicate features remain undamaged. They thoroughly pick the materials used in strengthening or repair specimens (Lockley et al. 161). Glues, adhesives as well as fillers have to stand the rest of time and not become discolored or brittle similarly to materials that aid in conserving works of art. The types of materials in use are recorded to aid in future in case extra preparation is needed.
Majority of the hard parts are porous instead of being solid. Pore space is covered by organic matter in life (Farlow et al. 457). After death, the latter starts the decaying process (Farlow et al. 457). The modes of preservation include unaltered, permineralized, recrystallization, replacement and carbonization. A scientist will carry out simple burial and some weathering in the unaltered approach. The pemineralized strategy is the most common among all of them.
Ground water is used to fill in a pore space. Some dissolved minerals form at the top of the pores. Common minerals discovered in fossils that have undergone through this process include calcite and silica. Initial hard parts remain but additional material is added to the pores. There are instances whereby soft tissues are permineralized but is rare. The third mode is recrystallization which common in fossils having calcite.
After burial, calcitic crystals reform and grow into one another. Initial mineralogy remains but the structure fails to exist anymore. The other modes include replacement and carbonization whereby in the former, partial to full crystals replacement of a single mineralogy with another happens. In the other approach, under pressure, the organic matter is distilled. In the process, many volatiles are lost but the carbon film remains (Novas 730). Additionally, soft tissues are preserved such as some dinosaurs’ feathers.
Identifying Fossils
When establishing whether something is a fossil, the first step by a paleontologist is checking weight. A material that is fossilized is filled with many minerals. This often means that there will be an increase in weight (Zipko 435). The bone is much heavier than a normal one and any individual can immediately notice that. Therefore, if an investigator finds a heavy object, they initially assume it is a fossil.
After checking for the weight, color is the next thing a paleontologist notices. In the event an object has much weight and appears as to have a light color, it is often not a fossil unless it has a clear imprint inside it, for example, shells in limestone. Nevertheless, mostly heavy and lightly colored objects are rocks such as flint. A scientist assesses the surfaces of possible fossils (Farlow et al. 470). If they seem smooth and lack an actual texture, they are likely rocks. Even if it appears in the shape of a bone and does not possess the right texture then it is perhaps a rock.
Lastly, a paleontologist does a final inspection of the probable fossil by checking for availability of pores. These are small holes that can be seen in bones as a feature of the structure. Some parts of the bones have these holes while others are denser where it can be hard to see or feel the pores. When holding a fossil bone, the holes can easily be seen without the need of a magnifier. If they are absent then the material one is investigating is just a petrified wood. This is a plant equivalent of a bone or the mineralized remains of a tree’s toughest part.
There is an alternative way of identifying a fossil that is less recommended by scientists in the field. As mentioned earlier, the bones are porous (Boyacigiller et al. 270). The function of the holes is strengthening and allowing liquid or air to pass through. This means that one method that can be used by a paleontologist to check for presence of a fossil is by putting the potential material on their tongue. In case it sticks then it is positive but if it fails to do so, it is negative. Whereas this technique can be effective, the ramifications are apparent and thus, the main reason why using a flow chart is better.
Conclusion
The paper reveals that a dinosaur can be described as reptiles of the clade Dinosauria group. Historians claim that they initially appeared during the Triassic era which is more than two hundred million years ago. They gained dominance as terrestrial vertebrates after the extinction that occurred two hundred million years ago. It is believed that birds are the modern and feathered version of dinosaurs that evolved from past theropods in the Late Jurassic age. They are the only ones in the lineage to survive the extinction event about sixty-six million years ago. Therefore, a dinosaur can be divided into avian and non-avian, the latter being extinct.
The paper also informs that majority of the ancient animals never reached a point of becoming a fossil. The carcasses after dying were probably consumed by organisms or worn away by water or wind. However, there are times that the conditions were suitable and the remains were preserved. The most common procedure of fossilization occurs when an animal is buried by sediment such as silt or sand shortly after death. As decomposition continues, every fleshy part wears away and only the hard structures, for example, horns and teeth, remain. When identifying whether an object is a fossil, the paper suggests that the first step by a paleontologist is checking weight. A material that is fossilized is filled with many minerals. This often means that there will be an increase in weight.
The bone is much heavier than a normal one and any individual can immediately notice that. Therefore, if an investigator finds a heavy object, they initially assume it is a fossil. After that, it is transported to a laboratory where further exploration occurs. An individual who prepares fossils is highly skilled technician who extracts from the surround matrix, uses consolidants and adhesives to stabilize them and prepare casts and molds of the specimens. When a fossil arrives from the field, it is encased in plaster jackets, and the rock or matrix which surrounds it. Preparation involves cutting open the jacket as well as eliminating the matrix covering the fossil. There is another way of checking whether an object is a fossil. However, due to the downsides of the method, experts do not recommend it. A paleontologist to check for presence of a fossil is by putting the potential material on their tongue. In case it sticks then it is positive but if it fails to do so, it is negative.
Works Cited
Bakker, Robert T. “Dinosaur renaissance.” Scientific American vol. 232, no. 4, 1975, pp. 58-79. Web.
Boyacigiller, Nakiye Avdan, and Nancy J. Adler. “The parochial dinosaur: Organizational science in a global context.” Academy of management Review vol. 16, no. 2, 1991, pp. 262-290. Web.
Farlow, James O., Peter Dodson, and Anusuya Chinsamy. “Dinosaur biology.” Annual Review of Ecology and Systematics vol. 26, no. 1, 1995, pp. 445-471. Web.
Lockley, Martin, and Christian Meyer. Dinosaur tracks and other fossil footprints of Europe. Columbia University Press, 2000. Web.
Novas, Fernando E. “Dinosaur monophyly.” Journal of vertebrate Paleontology vol. 16, no. 4, 1996, pp. 723-741. Web.
Zipko, Stephen J. “An Interdisciplinary Approach to Dinosaur Fossils, Morphology, Ethology, and Energetics.” The American Biology Teacher vol. 43, no. 8, 1981, pp. 430-439. Web.
Appendices
Appendix I
Appendix II
Appendix III
Appendix IV
Appendix V
Appendix VI
