The subphylum Hexapoda, known for a common body structure consisting of the famous three pairs of legs, abdomen, thorax and head, is divided into two taxonomic groups: the Entognatha and the Ectognatha (Sasaki et al., 2013). Within the Entognatha are the orders Diplura, Collembola, and Protura (Sasaki et al., 2013). These are all wingless orders (Sasaki et al., 2013). The Entognatha are marked by an entognathy, which is seen as their mouthparts being further inside their head, being enclosed by extensions of the head (Reiger et al., 2004). Within the Ectognatha is the class Insecta (Sasaki et al., 2013). This is further subdivided into the orders Pterygota, Zygentoma, and Archaeognatha (Sasaki et al., 2013). Ectognatha are classified by an ectognathy, which is the presence of exposed mouths (Sasaki et al., 2013).
The relationships between each class and order within the two taxonomic groups are not concrete due to much dispute. After sequencing the ribosomal RNA of the orders Diplura, Protura, and Collumbola, it was found that Diplura is most closely related to Protura, making them sister groups (Luan et al., 2005). Together, these orders are termed “Nonoculata,” which is in reference to their lack of eye structures (Luan et al., 2005). It was also found that Collembola is most closely related to the Nonoculata, making them sister groups as well (Luan et al., 2005). Based on a study (Nardi et al., 2003) using amino acid sequencing data, the subphylum Hexapoda was considered diphyletic, or split into two main taxa (Reiger et al., 2004). These are the Entognatha taxonomic group and the Insecta class (Reiger et al., 2004). By using this sequence data, it was found that class Insecta are more closely related to the Crustacea subphyl...
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...red to the abundance of marine fossils of early Crustacea (Grimaldi, 2010). Despite this gap in the fossil record, the molecular evidence proving the evolutionary relationship between Hexapoda and Crustacea proves to be both compelling and consistent (Grimaldi, 2010).
Molecular and morphological data have been proven to be influential in determining the phylogenetic relationship of Hexapoda and its role in the scheme of evolution. However, when comparing different characteristics of the organisms, such as morphology and molecular sequences, many different phylogenies can be created from the analysis of the data (Reiger et al., 2004; Sasaki et al., 2013). The debate to find the most plausible phylogeny will continue to go on, because different accurate phylogenies can be created depending on the focus of the researcher (Reiger et al., 2004; Sasaki et al., 2013).
Their classification is as follows.... ... middle of paper ... ... Works Cited 1) Carroll, R. L. 1988. Vertebrate Paleontology and Evolution.
Pianka, E. and Hodges, W. 1995. Horned Lizards. University of Texas. Web. Accessed at http://uts.cc.utexas.edu/~varanus/phryno.html
Xu, X., Zhou, Z., Prum, R.O. 2001. Branched integumental structures in Sinornithosaurus and the origin of feathers. Nature 410: 200-203.
The origin of modern day whales, a mystery that has puzzled paleontologists for years, may have just been solved with the discovery of an ankle bone. This discovery might sound simple and unimportant, but the bones of these ancient animals hold many unanswered questions and provide solid proof of origin and behavior. The relationship between whales and other animals has proven to be difficult because whales are warm-blooded, like humans, yet they live in the sea. The fact that they are warm-blooded suggests that they are related to some type of land animal. However, the questions of exactly which animal, and how whales evolved from land to water, have remained unanswered until now.
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
University of California Museum of Paleontology. Introduction to the Palaeognathae. 20 August 1995. Web. 1 March 2014.
There are nearly one million species of insects known. Insects are defined by having six legs and a body divided into three segments: head, thorax, and abdomen. Chitin is an organic material that makes up an insects exoskeleton. There are three life cycles of insects, ametabolous or incomplete and paurometabolous or gradual, and homotabolous or complete metamorphosis. These life cycles are important in the aging of insects for aiding in legal investigations, (Houck and Siegel. Entomology).
...o happen. But with the help of fossil evidence we are able to identify common ancestors and evolutionary pathways between species. We also identify oxygen as a major key contribution for life to evolve. Also, through scientific research it has been established that arthropods and chordates have shared genes, leading to the path of vertebrates and human life.
With its abundance of genera, the Burgess Shale is one of the world’s most important fossil fields. It’s discovery in 1909 led to over 100 years of paleontological study in the Canadian Rockies, a majority of which has been carried out in two quarries known as the Walcott and Raymond quarries (Hagadorn, 2002). Though he was originally in search of trilobites in the Burgess Shale Formation, paleontologist Charles Walcott also discovered a diverse group of soft- and hard-bodied fossils, from algae and sponges to chordates and cirripeds (Hagadorn, 2002). Soft-bodied fossils are incredibly rare due to their delicate structure and susceptibility to decay, so it is hard-bodied fossils that more regularly occur in fossil findings. However over 75,000 soft-bodied specimens have been found in the Burgess Shale formation (Hagadorn, 2002). These specimens are preserved in layers of shale formed from deposits of fine mud. One of the most significant species discovered is the Pikaia gracilens. Believed to be an early chordate, the Pikaia gracilens existed very close to the beginning of the evolutionary path that ultimately lead to humans (McGraw-Hill Encyclopedia, 2006).
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.
When these alterations are helpful, they grow to be fixed in a population and can result in the evolution of new phyla. Evo-devo seeks to figure out how new groups happen by understanding how the method of development has evolved in different lineages. In other word, evo-devo explains the interaction between phenotype and genotype (Hall, 2007). Explanation of morphological novelty of evolutionary origins is one of the middle challenges in current evolutionary biology, and is intertwined with energetic discussion regarding how to connect developmental biology to standard perspectives from the theory of evolution (Laubichler, 2010). A large amount of theoretical and experiential effort is being devoted to novelties that have challenged biologists for more than one hundred years, for instance, the basis of fins in fish, the fin-to-limb change and the evolution of feathers.
Reptiles are vertebrate, or backboned animals constituting the class Reptilia and are characterized by a combination of features, none of which alone could separate all reptiles from all other animals.The characteristics of reptiles are numerous, therefore can not be explained in great detail in this report. In no special order, the characteristics of reptiles are: cold-bloodedness; the presence of lungs; direct development, without larval forms as in amphibians; a dry skin with scales but not feathers or hair; an amniote egg; internal fertilization; a three or four-chambered heart; two aortic arches (blood vessels) carrying blood from the heart to the body, unlike mammals and birds that only have one; a metanephric kidney; twelve pairs of cranial nerves; and skeletal features such as limbs with usually five clawed fingers or toes, at least two spinal bones associated with the pelvis, a single ball-and-socket connection at the head-neck joint instead of two, as in advanced amphibians and mammals, and an incomplete or complete partition along the roof of the mouth, separating the food and air passageways so that breathing can continue while food is being chewed. These and other traditional defining characteristics of reptiles have been subjected to considerable modification in recent times. The extinct flying reptiles, called pterosaurs or pterodactyls, are now thought to have been warm-blooded and covered with hair. Also, the dinosaurs are also now considered by many authorities to have been warm-blooded. The earliest known bird, archaeopteryx, is now regarded by many to have been a small dinosaur, despite its covering of feathers The extinct ancestors of the mammals, the therapsids, or mammallike reptiles, are also believed to have been warm-blooded and haired.
The world we live in today is full of an exceptional variety of animals. The time it took to conclude to the various sorts of species seen today has been throughout a period of millions of years. The vast majority of these animals are accredited to evolutionary advancements. When the environment changes, organisms have become accustomed to changing to fit their environment, to ensure their species does not die off. These physical changes have resulted in different phyla, ranging from basic structures, like sponges to advance systems, like that of an octopus.
Insect, small, air-breathing animal characterized by a segmented body with three main parts—head, thorax, and abdomen. In their adult forms, insects typically have three pairs of legs, one pair of antennae, and in most instances, two pairs of wings. Insects rank among the most successful animals on Earth. About one million species of insects have been identified so far, which is about half of all the animals known to science. That is why for every pound of human on the earth there are 10 pounds of insects. So that is why there are many reasons why insects are so successful, their exoskeleton, their size, their body function, the way they reproduce, and their development of metamorphosis.
Most of the species from habitat one are Diptera. There was a total of thirteen Diptera’s in habitat one. Cup one had the least amount of individual species with four. Habitat two had more individual species than habitat one. There was a total of seventy-nine species from habitat two. Like in habitat one most of of the arthropods from habitat two were Diptera. The was a total of eighteen Diptera’s in habitat two. Cup six had most of the Diptera’s with thirteen. Orthoptera was second in the number of individuals with sixteen. Orthoporea’s are crickets and