animalia-notocord-nerve cord-visceral (pharyngeal, gill) clefts or arches
hagfish (Myxinikela)330mya late C
lamprey (Mayomyzon, Hardistiella, Pipiscius) lateC of USA
anaspids? or lampreys
-Jamoytius (Early Silurian of Scotland)
-Euphanerops (Late Devonian of Canada)
Euconodonts (Middle Cambrian (540 million years) to the Late Triassic (230 million years);Carboniferous of Scotland; Ordovician of South Africa.)
Pteraspidomorphi, or pteraspidomorphs, is a group of fossil jawless vertebrates Early Ordovician to the Late Devonian (i.e. from 470 to 370 million years ago
he Anaspida, or anaspids, are a group of fossil, jawless vertebrates which lived in the Silurian (-430 to -410 million years ago)
The Galeaspida, or galeaspids, are a highly diversified group of fossil, armored, jawless vertebrates, which lived in Silurian and Devonian times (430 to 370 million years ago).
The Pituriaspida are a small group of fossil, armored jawless vertebrates, only known by two genera, Pituriaspis and Neeyambaspis, from the late Early Devonian or early Middle Devonian (about 390 million years) of Queensland, Australia
The Gnathostomata, or gnathostomes, are the majority of the Middle Devonian (-380 million years ago) to Recent vertebrates. Extant gnathostomes fall into two major clades, the Chondrichthyes and Osteichthyes. In addition, there are two extinct major gnathostome clades, the Placodermi (Early Silurian-Late Devonian) and the Acanthodii (Latest Ordovician or Earliest Silurian - Early Permian).
The oldest known skeletal remains of terrestrial vertebrates were found in the Upper Devonian of East Greenland (Clack, 1994). The presence of Lower to Middle Devonian trackways in Australia has led to suggestions that this group may have originated in the Lower Devonian, at least 400 million years ago (Tetrapods originated no later than the Mississippian (about 350 million years ago), the period from which the oldest known relatives of living amphibians are known.The oldest amniotes currently known date from the Middle Pennsylvanian locality known as Joggins, in Nova Scotia (Carroll, 1964). The relationships of these fossils indicate that amniotes first diverged into two lines, one line (Synapsida) that culminated in living mammals, and another line (Sauropsida) that embraces all the living reptiles (including birds). ... suggests that the more inclusive clade of which turtles (Testudines) are part (Anapsida) in most
morphological phylogenies had diverged as well, even though its current record extends back only to the Lower Permian (Laurin & Reisz, 1995). The earliest known salientian is †Triadobatrachus massinoti, from the Early Triassic of Madagascar. This "proto-frog" is about 250 million years old. "Proto-frog" refers to the fact that it had not yet quite evolved
the combination of features that are typically associated with frogs. For more information see
†Triadobatrachus massinoti. The earliest "true" frogs include †Prosalirus bitis and †Vieraella herbsti, from the Early Jurassic era. Thus, perfectly respectable frogs were around just before most of the major groups of dinosaurs had appeared. †Notobatrachus degiustoi from the Middle Jurassic is just a bit younger, about 155-170 million
Actinopterygii-earliest Devonian-dominant by late paleozoic-paleoniscoids C to Triassic, extinct by end of Mesozoic (sturgeon, paddlefish relatives)-holosteans MZ (bowfish rel)-teleosts late Triassic dom by CZ
Sarcopterygii lobe-finned fish(lower Devonian) & tetrapodscentral appendage in fins, enamel on teeth, asymmetric tail originally
Anapsids mid-Pen AmphibiansElginerpeton 368mya ScotlandIchthyostega 363mya Greenland
Vertebrates: Fossil Record Because bone is resistant to decay, the fossil record of vertebrates is extensive and has been studied for over 200 years. We can't present all of it on one page; visit our exhibits on specific vertebrate groups for more detailed information. But to give a very brief summary:
The first known vertebrate fossils, found at the Chengjiang locality in China, date back to the early Cambrian. These early vertebrates, such as Haikouichthys, are small, tapered, streamlined animals showing eyes, a brain, pharyngeal arches, a notochord, and rudimentary vertebrae. Vertebrates appear to have radiated in the late Ordovician, about 450 million years ago. However, most Ordovician fossil fossil vertebrates are rare and fragmentary, although available material suggests that ancestors of the sharks and jawed fish were present along with various lineages of armored jawless fish. By the middle Silurian, about 400 million years ago, the picture is clearer: the armored jawless fish were quite diverse, and the first definite jawed fish had appeared -- the Silurian is sometimes called the "Age of Fishes." By the late Devonian, 360 million years ago, early cartilaginous fish and bony fish were diversifying. The late Devonian also marked the first tetrapods -- vertebrates with true legs that could walk on land. By about 330 million years ago, in the Mississippian, several groups of land-dwelling amphibians had appeared. The oldest known amniotes -- close to the ancestry of all reptiles, birds, and mammals -- appeared in the early Pennsylvanian, about 310 million years ago. Land amniotes continued to diversify, and by the middle Pennsylvanian had split into several taxa, two of which would go on to dominate the Mesozoic and Cenozoic: the diapsids and the synapsids.
All reptiles except turtles (incl dinos and birds)diapsids evolved into many shapes, occupying many different ecological niches since they first came onto the scene in the late Carboniferous period (roughly 350 million years ago), when they were represented by the earliest diapsid, the tiny lizardlike Petrolacosaurus
Synapsid classification has undergone tremendous change in recent years; most of the traditional groupings have been discovered to be paraphyletic. To represent this, we have used multiple lines drawn to paraphyletic groups in the cladogram above. Except for the Mammalia, all synapsid groups are extinct.
Current hypotheses about early synapsid diversification suggest that "pelycosaurs" are the basal-most synapsids, and are certainly paraphyletic. This group includes familiar "sail-back" critters like Dimetrodon, but also includes a variety of lesser known early synapsids, such as the herbivorous Caseidae. All groups of pelycosaurs went extinct by the end of the Permian. The remaining groups in the above cladogram constitute the Therapsida, and most of them diversified in the Permian or Triassic -- and then disappeared as the dinosaurs came to dominate the terrestrial world.
the·rap·sid /θəˈræpsɪd/ Pronunciation Key - Show Spelled Pronunciation[thuh-rap-sid] Pronunciation
Key - Show IPA Pronunciation –noun 1. any of various groups of mammallike reptiles of the extinct order Therapsida, inhabiting all continents from mid-Permian to late Triassic times, some of which were probably warm-blooded and directly ancestral to mammals. –adjective 2. of or pertaining to the Therapsida.
[Origin: < NL Therapsida (1905), equiv. to Gk thér- (s. of thr wild beast) + apsid- (s. of apsís arch, vault, referring to the temporal arch of the skull) + NL -a neut. pl. ending (see -a1)]
sauropod (sôr'ə-pŏd') Pronunciation Key One of the two types of saurischian dinosaurs, widespread during the Jurassic and Cretaceous Periods.
Sauropods were plant-eaters and often grew to tremendous size, having a stout body with thick legs, long slender necks with a small head, and long tails. Sauropods included the apatosaurus (brontosaurus) and brachiosaurus. Compare theropod.
noun any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs WordNet® 3.0, © 2006 by Princeton University. The American Heritage Science Dictionary - Cite This Source - Share This theropod (thîr'ə-pŏd')
Pronunciation Key Any of various carnivorous saurischian dinosaurs of the group Theropoda. Theropods walked on two legs and had small forelimbs and a large skull with long jaws and sharp teeth. Most theropods were of small or medium size, but some grew very large, like Tyrannosaurus. Theropods lived throughout the Mesozoic
Era. Compare sauropod.
ac·ti·nop·te·ryg·i·an /ˌæktəˌnɒptəˈrɪdʒiən/ Pronunciation Key - Show Spelled ronunciation[ak-tuh-nop-tuh-rij-ee-uhn] Pronunciation Key - Show IPA Pronunciation –adjective 1. belonging or pertaining to the Actinopterygii, a group of bony fishes. –noun 2. an actinopterygian fish.
[Origin: < NL Actinopterygi(i) (pl.) (actino- actino- + Gk pterýgi(on) fin, equiv. to pteryg- (s. of ptéryx wing) + -ion dim. suffix) + -an]
sarcopterygian (sär-kŏp'tə-rĭj'ē-ən) Pronunciation Key See lobe-finned fish.
Sarcopterygii (from Greek sarx, flesh, and pteryx, fin) is traditionally the class of lobe-finned fishes, consisting of lungfish and coelacanths.
CharacteristicsThese are bony fish with paired rounded fins. These fins, being similar to limbs, suggest that these fish may be ancestors of land vertebrates.Most taxonomists who subscribe to the cladistic approach include the grouping Tetrapoda within this group, which in turns consists of all species of four-limbed vertebrates. The fin-limbs of sarcopterygiians show such a strong similarity to the expected ancestral form of tetrapod limbs that they have been universally considered the direct ancestors of tetrapods in the scientific literature.
Evolution of Sarcopterygii
Sarcopterygians belong to Osteichthyes group or bony fishes, characterized by their bony skeleton instead of cartilage. The oldest Sarcopterygians were found in the Uppermost Silurian. The first Sarcopterygian closely resembled Acanthodians. The Sarcopterygians closest relatives were the Actinopterygians - ray-finned fishes. Sarcopterygians probably evolved in the oceans, but they later came into freshwater habitats to avoid the predatory placoderms - which were dominant in the Early - Middle Devonian seas.
As Sarcopterygians evolve in the Early Devonian, the line splits into two main lineages - the Coelacanths, and the Rhipidistia. The Coelacanths appeared in the Early Devonian, and stayed in the oceans; the coelacanths' heyday was the Late Devonian and Carboniferous, as they were more common during those periods than in any other period in the Phanerozoic. Coelacanths still live today in the oceans. Rhipidistians appeared about the same time as the Coelacanths, but unlike them, Rhipidistians left the ocean world and migrated into the freshwater habitats, their ancestors probably lived in the oceans near the river mouths (estuaries). The Rhipidistians in turn split into two major groups - the lungfishes, and the tetrapodomorphs. The lungfishes' greatest diversity was in the Triassic Period, but today, there are fewer than a dozen genera left. The lungfishes evolved the first proto-lungs and proto-limbs. The lungfishes, ancient and modern, used their stubby fins (proto-limbs) to walk on land and find new water if their waterhole was depleted, and used their lungs to breathe air and get sufficient oxygen. The tetrapodomorphs have the same identical anatomy as the lungfishes, who were their closest kin, but the tetrapodomorphs appear to have stayed in water a little longer until the Late Devonian. Tetrapods - four legged vertebrates were the terapodomorphs' descendants. Tetrapods appeared in the Late Devonian epoch. Non-tetrapod sarcopterygians continued to towards the end of Paleozoic Era. They suffered heavy losses during the Permian-Triassic extinction event.
tel·e·ost (těl'ē-ŏst', tē'lē-) Pronunciation Key adj. Of or belonging to the Teleostei or Teleostomi, a large group of fishes with bony skeletons, including most common fishes. The teleosts are distinct from the cartilaginous fishes such as sharks, rays, and skates.
n. A teleost fish.
[From New Latin Teleosteī, group name (Greek teleos, complete; see teleology + osteon, bone; see ost- in Indo-European roots) and from New Latin Teleostomī, group name (Greek teleos, complete + Greek stoma, mouth).]