Homo Erectus Species - Essay Example

COMPARATIVE ANATOMY ASSIGNMENT Homo erectus species cannot be easily distinguished from current species of Homo sapiens when this kind of hominid is clothed in modern style. The evolution of Homo erectus ranges from 2.0-0.4 MYA with each species located in parts of Africa, China, and even Europe. The primary reason Homo erectus is seen as the most variable species, with individual species varying in height, bone mass and other traits. The difference between fossils from various locations can be seen. For example, fossils found in parts of China and Indonesia has been existent in a smaller body size than those found in Africa. Some of the fossils propose a geographical diversity and a difference in characteristics are KNM-ER 1808 and Trinil 2. In 1891, an archeologist named Eugene Dubois found angular, domed, and thick-walled human skullcap with a large shelf like brow ridge near Trinil, Java (Indonesia. He decided that the skull be named Trinil2 (Dorey). Another person, Kamoya Kimeu in 1974 discovered a 1.7 million years old femur of Homo erectus KNM-ER1808 in Koobi Fora in Kenya. This female Homo erectus has an incredible distinct feature that surprised the researchers; it has an abnormal layer of bone on her thigh that shows evidence of bleeding to her death. Scientists have concluded that it is an overdose of vitamin A. The two skulls have some significant differences between them. Trinil 2 has a long, flat forehead, distinct brow ridges and have sagittal keel (Dorey). The cranium of Trinil 2 is thick brow ridges that are sharply angled rear where the neck muscles attach. When the Trinil femur is compared with KNM-ER 1808, one will see that Trinil is considerably ‘human’ while the other is more of Homo erectus. The skeleton of KNM-ER 1808 has almost complete right femur but unfortunately lacking a head. LAB REPORT NAME THAT FOSSIL ASSIGNMENT There have numerous changes in the evolution of the hominid that have occurred. These changes have significantly contributed to the change in the proportion of the skull. Different parts of the skull in various hominids are varying proportion. The change from one hominid can be noticed in face size, shape, brain capacity and even position of occipital condyles. In this Lab report, we shall measure different proportions, calculate indices and compare them with known or commonly recognized hominines species. PROCEDURE 1. Look the figure 1 and identify points; inion, prosthion, porion in each skull. 2. When the location of the points are known, connect their location with lines (porion intersects lowest point of the eye orbit such that line almost touch top circle and bottom edge). As shown in the guides. 3. Measure the length of the lines; uv, tv, tw, xy, and xz. 4. Record the data in the chart and calculate three ratios (supraorbital height, nuchal area height and condylar position) 5. Use the result to analyze three mysteries skulls and identify the taxonomy status of each skull. RESULT AND ANALYSIS MYSTERY SKULL 1 The ratio uv/tv of is 38.9, and hominid has small supraorbital height. The ratio show the specimen has small braincase. The nuchal area height is lower compared than the forehead. The condylar position index is very high that it deduces that foramen magnum is at the front of the skull. Also, high condylar position shows large posterior skull. Physical traits: Mystery Skull #1has a long back extension than the facial profile. Has no sagittal crest, and pronounced brow ridges. The orbits (eye socket) are bigger than nasal opening The taxonomy status of Mystery #1 is Homo habilis because the base of the skull is reduced in the length but increasing width. The foramen magnum is relatively closer to the front of the skull. Compare the face and nasal, the face has decreased in width while the nasal opening is more sharply defined. MYSTERY SKULL 2 The ratio of supraorbital height is high. It is associated with significant brain capacity. The high supraorbital height shows that the skull forehead is slanting backward. The nuchal area height is a little lower compared to other indices. This show that hominid has bigger nuchal area than upper face part. The condylar position index is average; this means that foramen magnum is approaching the back of the skull. Physical traits: Mystery Skull #2 has cheek bones (zygomatic arch). This skull has small supraorbital torus (brow ridges). This skull has the Meso gnathic face that is slanting backward. The taxonomy status mystery skull #2 is Australopithecus. This is because of prognathism and zygomatic arch and low brow traits (Pilbeam). These characteristics are most associated with Australopithecus. NEWLY FOUND SKULL The supraorbital height index is slightly below average.It shows that medium brain capacity. The nuchal area height is very low; this shows that the skull has tall nuchal area compared to the upper face. The skull has the very high condylar index that show that foremen magnum is at the middle of the base of the skull. High condylar position ratio is also associated with evolving bipedalism Physical traits: The newly found skull has almost straight face i.e. ortognathic face. The skull also do have large angle forehead slope. There are brow ridges. The skull has the sharp angle at the back of the skull. The taxonomy status is Homo erectus because the face is large with a low sloping, massive brow ridge, broad flat nose, and skull is broad with the sharp angle at the rear. Though there are features, the skull is more to be Homo erectus. CONCLUSION With many images of hominid skulls readily available in the literature materials, students can use quantitative measures and construct the mathematical index that relates these features of the hominines to cranial capacities. The craniometrical analysis will help to compare the various skull data with the known measure of various hominids. This approach helps to describe and explore structural and functional changes that are associated with hominid evolution. Works Cited Dorey, Fran. Homo erectus. 11 September 2013. 4 May 2015 http://australianmuseum.net.au/homo-erectus Pilbeam, David. Morphological affinities of the Sahelanthropus tchadensis (Late Miocene hominid from Chad) cranium. 5 November 2005. 4 May 2015 . Read More