Historic and Contemporary Distributions of Equidae - Research Paper Example

Historic and contemporary distributions of Equidae Distinction between assortments, subspecies, and species appears uninformed often. In the present world, novel provides the opportunity of challenging hypothesis of the species (Bruce, pg. 26). Recently developed methods of testing species boundaries and relationships are often applied using multilocus data set consisting of two mitochondrial genes and one intron. The equids are the greatest copious and widely-distributed group of contemporary perissodactyls, though only one species and seven species survive to the present day. The present dispersal of the Equidae - open environments of Eastern and Southern Africa and expanses of Asia - is expressively abridged from past times, a form seen amid all perissodactyls (Croft, pg. 103). Contemporary horses are well modified to the plains, prairie lands, and deserts that they dwell; their teeth are high-crowned to handle with rough vegetation and their appendages are long and lean, with just a single toe, for improved running competence. The history of Equidae is rich in Mexico and limited in Central America (Carnelli et al, pg. 425). There is no direct relationship between climate and overall brusqueness of the species. There is slight potential for displaying climate variables and climate alteration from tooth wear deputations. Nevertheless, tooth wear substitutions can be used to conclude local nutritional qualities of populaces and track them over and done with interplanetary and phase. Introduction Equidae is kinfolk of odd-toed ungulate mammals of horses and horselike creatures (Bruce, pg. 78). It is occasionally known as the horse family. All surviving equids are in the genus Equusand embrace the three simple groups of horses, asses, and zebras. There are eight to ten extant species in Equidae, dependent on the taxonomic outline (Carranza et al, pg. 249). Croft pg. 117(2008) recognized and classified nine distinct species within the genus Equus. Geographical ranges of all these species have declined significantly over the years and are becoming increasingly fragmented. Carranza et al, (pg. 257) consider reasonable elimination and detailed reworking to be the key causes of the present dispersal patterns. Dental formulas have been the key elements used in the past in the study of the evolution of these species. Most of the theories have developed on the basis of the answers arrived at by studying the teeth of these mammals. Even in the present ongoing research there has been no deviation from this approach. With the various advancements in the research discipline, fossils remains in the future need to be considered in deriving conclusions and bringing about a better understanding of these species (Kaiser, pg. 381). It is always important to consider various aspects that mold behavior rather than largely concentrating on the feeding patterns. Theoretical Analysis It is estimated that more than one hundred and forty thousand articles, journals, books and other scholarly articles have been written about Equidae and numerous researches conducted in an attempt to understand their origin and their behavior. Equids are hind-gut fermenters and ensue in grassland, semi-desert and desert environs. They are well adjusted to low-quality food (Carnelli et al, pg. 103-107), chiefly consuming enormous amounts of grass (Carranza et al, 257). Despite these resemblances amid species, each taxon has a precise continuum of nutritional sources. Equids are social animals living in herds or brands mainly consisting of single males and a bunch of females. There are clear hierarchies established among individuals usually with dominant female controlling access to food and resources while the dominant male controls access to mating sessions (Croft, pg. 118). Equus hydruntinus inhabited Europe and middle east more than 300,000 years ago (Croft 103). It shared a primitive Equus characters with both zebras and asses, and derived characters with Zebras and Hermione’s.Ancient. Samples were found in Crimea and Iran regions and a DNA analysis supports proximity of E. hydruntinus and Equus and rejects proximity to either asses or Zebras as it had been suggested earlier. There was a small genetic difference between the Equus remains found in Europe and those found in Iran. This species has become distinct in the contemporary world thus no geographical distribution of the same (Carranza et al 89-97). The oldest equids remain dates back to the early Eocene, 55 million years ago. This species was a fox-sized animal with three hind toes on its hind feet, and four on the front feet. It was herbivorous feeding on soft plants and was adapted for running. Bruce (pg. 179) suggests that it brain indicated that it was already an alert and intelligent animal. The main weight of their bodies was concentrated on their central body and third toe. In the old world, all equids were wild. Horses and donkeys started to be domesticated by man 350 thousand years ago. These species became relatively dispersed in the subsequent Miocene era. New species appeared which closely resembled modern horse with the contemporary typical bodies. Equine material was collected from the middle Miocene in Oaxaca, Mexico which consisted of 15 isolated cheeks teeth which portrayed three associated dental series. This new found evidence asserted earlier studies on dental formula of equines and their associated environments and feeding patterns. The dominant equine in the study of equids is pilohipus, a horse which roamed greatly along California coastal ranges, great basin and the great plains of gulf coastal plain. A partial skeleton was found in the coastal plains, which was associated with numerous subspecies which led to the discovery of Astrohippus which had a generic link to pilohipus. Within this context, Bruce, (pg. 174) regarded pliohippus as consisting of three successive groups which were all associated with California coastal plains as their origin. The history of these species in Mexico and North America is unfolded in consonance with the findings in California basin. Horses from Northern Mexico added two species in these findings, which were not a major finding because they were included in the pliohippus subspecies (Kaiser, pg. 389). However, the findings from southern Mexico were completely distinct from earlier findings from the North. An interest account was that there was no mammal resemblance with prior findings. 15 isolated teeth checks were discovered which were compared with the dental formulas of those in North Mexico and California which showed a little varying pattern. Distributions in the contemporary world Despite the low numbers of equids in the present world, geographic distribution of the same has been recorded. In South America, the widely distribute Equidae relates to the genus Equus neogeus. It is highly concentrated in the Argentina region. Nothofagus dominates the landscapes of central-south Chile which are covered by temperate rain forests. Zebras are found in the Savannah of Africa with horses found in all parts of the world today. This has been aided by domestication of these animals. Results Equines from Mexico were known from the Hemphillian and Blancan of numerous morspecies photectonic provinces. The exploration of Pliohippus sp. from Oaxaca geographically spreads southward the Equini best ever from the Trans-Mexican Volcanic Belt to the Sierra Madre del Sur MP, and inaugurates equines in a tropical environment. Teeth wear discovered in these researches suggested two outcomes; abrasion (tooth-food contact) and attrition (tooth-tooth contact). Animals with abrasion subjugated tooth garb have duller tips with subordinate break, and animals with attrition-dominated tooth wear progress high-pitched nibs with sophisticated reliefs. Thus, irrespective of equine origin, it dental formula speaks much of its inhabitants, and there have never been controversial findings on this account. Discussions Despite the evidence of various researches on these species, one might be interested to understand why keep on studying this topic while the findings from various researches has had almost similar results. For instance, most researches signify that climatic conditions impacted the animal’s diet and with time molded them to be the way they are in the present world (Bruce, pg. 309). It is important to understand that all these findings are theories which can be challenged. With the advancement in technology, new evidence might thus be found which can provide a major breakthrough. As time progresses, yester information can become absolute and be deemed unreliable and regarded useless thus the need to keep researching and gathering more information to support these theories until a time when unified conclusions are arrived at (Croft, pg. 120). Conclusions and Summary Worldwide, there is spatial distribution of wild Equidae. They are mostly found in mountainous or semi-mountainous regions. In Africa they are used for tourist attraction while most of them are used as working animals. Recording of the distribution of these animals subspecies is an enormous task in the contemporary world. This is so because of increased mankind activities which has greatly interfered with fossils remains leaving nothing behind for researchers to rely on. Most of advancement in the modern world have done very little to alter their organizations. The wild ones are always seen in herds where they live as a family. In the modern world, they have significantly reduced in numbers compared to the Old world. This can be attributed to changes in climatically conditions as well as poaching activities. Domestication as also contributed to their decrease as those that are kept at home is always restricted by owners when it comes to reproduction (Kaiser, pg. 393). Equines differ in their physical and feeding patterns depending on the areas where they are found. For instance, those found in cold area are covered with fur and have a layer of fat beneath their skin while those found in the desert and semi-desert areas have less far. This also signifies varying flexibility of these species (Croft, pg. 117). The evolutionary process of any creature is said to be random, stochastic with no purposeful design for nature. However, whether consciously or unconsciously, evolution even of the human species takes place without any doing on anyone part. Therefore, as further research is conducted on this area, this reality should be taken into consideration. Changes should be noted and effort directed towards understanding the reason behind such changes. Since the time of ‘Darwin’, survival has been for the fittest as the struggle for existence continues. This can also explain the available evidence of diminishing numbers of equines over time. The weak species might have become exhausted along the way, but this statement is subject to further research (Kaiser, pg. 397). From the past occurrences in research, unidirectional trends have always been noted to occur which have not been explained but it has been argued that they have in a way contributed to the evolution process in the long term. In many instances, this has led to ambiguity. These facts are very real and should be given priority in conducting further research. Dispersal of equines needs to be studied in isolation from their history because from the above theoretical analysis it is clear that it is a wide area which needs more attention. This should further be subdivided in the study of different continents’ for a clear understanding. This would enhance the understanding and the various histories from these different continents should then be assembled together to point out the similarities and figure out the points of divergence of these histories. This would greatly aid the understanding of animal behavior and their social and spatial organization in the wild (Kaiser, pg. 401). In conclusion, despite the numerous efforts of different authors and researchers in the past in equines discipline, it is evident that agreement has not yet been arrived at especially in relation to the history and dispersal of these species. For instance, the Oaxacan record is contemporaneous. Works Cited Carranza-Castañeda, O., Miller, W.E., (2008), Late Tertiary terrestrial mammals from Central Mexico and their relationship to South American inmigrants: RevistaBrasileira de Paleontologia, 7(2), 249-261. Carnelli AL, Madella M, Theurillat J-P (2009) Biogenic silica production in selected alpine plant species and plant communities. Annals of Botany 87: 425–434. Croft DA, Weinstein D (2008) The first application of the mesowear method to endemic South American ungulates (Notoungulata). Palaeogeography, Palaeoclimatology, Palaeoecology269:103–114. Kaiser TM (2009) The dietary regimes of two contemporaneous populations of Hippotheriumprimigenium(Perissodactyla, Equidae) from the Vallesian (Upper Miocene) of Southern Germany.Palaeogeography, Palaeoclimatology, Palaeoecology198: 381–402. Anonymous (2009) The IUCN Red List of Threatened Species. http://www.iucnredlist.org/ Bruce.JMacfadden. Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae . Cambridge University Press, Jun 24, 2009 - 384 pages Read More