May 29, 2018 · However, many extinct agnathans had extensively developed bony plates directly under the skin. These were most often found in the region of the skull and served as a protective armor. Bony plates are not present in extant agnathan species. Major Groups of Living Agnathans. There are two major groups of living agnathans, the lampreys and the hag ...

The Agnathans are classified into two groups, myxinoids (hagfishes) and petromyzonids (lampreys). The Gnathostomes constitute all the other living vertebrates, including the bony and cartilaginous fishes and the tetrapods.

The agnathans probably arose as the first vertebrates about 550 million years ago, immediately after the evolutionary explosion of multicellular organisms in the Cambrian period. Paleontological analysis of extinct agnathans suggests that lampreys are more closely related to gnathostomes (the jawed vertebrates) than either group is to the ...

May 17, 2018 · The very first primitive fishes appeared, slow and heavily armored, without fins or heads with brains. These agnathans (jawless fishes) were the first animals to have a notochord (flexible rod spine), a precursor of a true spinal chord. These chordates were the ancestor of all animals with backbones.

May 23, 2018 · *Gnathostomata* *1.* A superclass of jawed vertebrates that includes the fishes, Amphibia [1], Reptilia [2], Aves [3], and Mammalia [4].

Lampreys and Hagfishes. Lampreys. Hagfishes. Interactions with humans. Resources. Lampreys and hagfishes are unusual, jawless fish that comprise the orders Myxiniformes (hagfishes) and Petromysoniformes (lampreys).

Human and Primate EvolutionHUMANS AMONG THE PRIMATESMIOCENE APESTHE FIRST HOMINIDSFROM AUSTRALOPITHECUS TO HOMOPLEISTOCENE HUMAN EVOLUTIONTHE NEANDERTHALSBIBLIOGRAPHY Source for information on Human and Primate Evolution: Encyclopedia of Race and Racism dictionary.

A hominid is a family of primates that includes today's humans and their extinct direct ancestors. Before humans evolved into what they are today, several human-like species existed, some of which went extinct and some of which evolved into today's species—the only …

COELACANTHS AND LUNGFISHES: SarcopterygiiCOELACANTH (Latimeria chalumnae): SPECIES ACCOUNTSSOUTH AMERICAN LUNGFISH (Lepidosiren paradoxa): SPECIES ACCOUNTSPHYSICAL CHARACTERISTICSCoelacanths (SEE-lah-kanths) and lungfishes have rounded, fleshy fins.

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