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· Registered
1,060 Posts
If you believe that we are nothing more than modified monkeys, who are also nothing more than modified lizards, who are nothing more than modified protozoa, ad infinitum, then you have far greater concerns than the Presidential nominations.

· Silver Bullet member
36,347 Posts
Actually those monkeys, and we, are therapsids, of the class mammalia. Our closest relationship to lizards is both being in the amniota group which also includes some extinct families of animals all characterized by having amniote embryos, whether laid as eggs or carried by the female, that are protected and aided by several extensive membranes. Lizards are thus not in the evolutionary chain of humans but a seperate line, the class Sauropsida, while we are in the class Synapsida which split off from the other amniotes at least 320 million years ago.

Classification to order level, after Benton, 2004.

Series Amniota
Class Synapsida
Order Pelycosauria*
Order Therapsida
Class Mammalia
Class Sauropsida
Subclass Anapsida
Order Testudines (turtles)
Subclass Diapsida
Order Araeoscelidia
Order Younginiformes
Infraclass Ichthyosauria
Infraclass Lepidosauromorpha
Superorder Sauropterygia
Order Placodontia
Order Nothosauroidea
Order Plesiosauria
Superorder Lepidosauria
Order Sphenodontida (tuatara)
Order Squamata (lizards & snakes)
Infraclass Archosauromorpha
Order Prolacertiformes
Division Archosauria
Subdivision Crurotarsi
Superorder Crocodylomorpha
Order Crocodylia
Subdivision Avemetatarsalia
Infradivision Ornithodira
Order Pterosauria
Superorder Dinosauria
Order Saurischia
Class Aves
Order Ornithischia
Synapsids include mammals and all extinct amniotes more closely related to mammals than to reptiles. Synapsids are the dominant large terrestrial animals worldwide, and they have also invaded the oceans (whales, pinnipeds) and the air (bats). The oldest known synapsid is an ophiacodontid from the Middle Pennsylvanian (320 million years ago) of Joggins, Nova Scotia. By the Lower Permian, therapsids (the group that includes mammals and most of their Upper Permian and more recent relatives) had appeared (Laurin and Reisz, 1990, 1996). However, the oldest known mammal only dates back to the Jurassic (Rowe, 1988). The fossil record of synapsids is one of the most extensive of any groups of vertebrates. This fossil record has been used to illustrate the concept of evolution (Hopson, 1987) and to test macroevolutionary patterns (Kemp, 1985). The largest gap in this fossil record is between the Permo-Carboniferous synapsids and therapsids.

The fossil record provides conclusive evidence that synapsids are the first amniotes to diversify. Synapsids quickly became the most diverse, widespread and most common amniotes in the Late Carboniferous, and they maintained this predominant position throughout the Paleozoic. Only during the Early Mesozoic are the synapsids eclipsed by the evolutionary radiation of reptiles (Benton, 1983; Charig, 1984). Within the Late Carboniferous and Early Permian, two different herbivorous and several faunivorous synapsid groups can be recognized.

The fossil record suggests that during the Carboniferous and Early Permian, synapsids and other amniotes were restricted to the paleoequatorial and subequatorial regions. During the Late Permian, the distribution of synapsids, and of some of the other amniotes becomes cosmopolitan. However, the evidence for this pattern rests on rather weak negative evidence (i. e., no Permo-Carboniferous synapsids have been found outside paleoequatorial regions, but other areas have not been prospected intensively).

Early synapsids had a sprawling posture and a small brain, like most early tetrapods. The parasagittal gait characteristic of most mammals (Fig. 1) appeared gradually because some therapsids were apparently capable of sprawling and parasagittal gait, and this character may have appeared in the hind limb before the fore limb. Early synapsids were moderately large (body length between 50 cm and 3 m) and most were carnivorous or insectivorous, but caseids and Edaphosaurus were herbivorous. Mammals include the largest tetrapods that ever lived (the blue whale is larger than any dinosaur), as well as very small species.

Most mammals are viviparous, but the platypus (a monotreme) is oviparous, and most, if not all, non-mammalian synapsids were probably oviparous. All mammals have mammary glands, but the presence of these structures cannot be determined in extinct taxa. The oldest preserved synapsid hair appears to belong to a Middle Jurassic docodontan mammaliaform (a stem-synapsid) from China (Ji et al., 2006). However, hair is infrequently fossilized and the next oldest record is from a Paleocene multituberculate (Meng and Wyss, 1997). Therefore, its real date of appearance is unknown. The position of this group has been debated, but they are probably mammals (Rowe, 1988), so the presence of hair in multituberculates was predictible.

The earliest synapsids were probably ectothermic (their body temperature depended on the environment), as shown by the presence of a large "sail" on the back of edaphosaurids and some sphenacodontids. This sail was composed of greatly elongated neural spines that was grooved anteriorly and posteriorly to accommodate blood vessels, and skin probably connected all the neural spines together. This sail may have allowed these early synapsids to raise their body temperature faster than similarly-sized tetrapods lacking a sail. It was also thought that the sail was used to radiate excess heat into the environment, but recent studies suggest otherwise (Haack, 1986). The presence of the sail suggests that early synapsids lacked hair. Hair usually does not fossilize, but its presence in most monotremes, marsupials, and placentals suggests that it was present in their last common ancestor. Endothermy is also difficult to determine in extinct taxa, but it probably appeared slightly before the first mammal was born. The presence of epidermal horny scales cannot be determined in most fossil taxa, but bony ventral scales were primitively present, as shown by their presence in most reasonably complete fossils of early synapsids.

· Gold Bullet Member and Noted Curmudgeon
101,779 Posts
They are really good sliced thin and strir-fried with suitable vegetables for spring roll filling. Add a little nouc mam for flavor and Bob's your uncle...
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