Best Answer: I dated a fossil for awhile. Then I married her. Source(s). Carbon dating is useless to date fossils. Fossils are dated relative to one another by their position in the Geologic Column, and the strata of the Geologic Column are likewise. Absolute dating of both is done using radiochronology of various types, which have been cross-checked with one another and by the relative dating by layer of strata. Hera Sent Me · 1 decade ago.
Possibly the best known of all transitional fossils, the Berlin specimen of This is a tentative partial list of (fossil remains of groups that exhibits both "primitive" and derived traits). The fossils are listed in series, showing the transition from one group to another, representing significant steps in the evolution of major features in various lineages. These changes often represent major changes in morphology and anatomy, related to mode of life, like the acquisition of feathered wings for an aerial lifestyle in , or limbs in the / transition onto land.
Almost all of the transitional forms in this list do not actually represent ancestors of any living group or other transitional forms. noted that transitional forms could be considered , direct ancestors or collateral ancestors of living or extinct groups, but believed that finding actual common or direct ancestors linking different groups was unlikely. Collateral ancestors are relatives like cousins in genealogies in which they are not in your direct line of descent but do share a common ancestor (in this case it is a grandparent).
This kind of thinking can be extended to groups of life. For instance, the well-known is a transitional form between non-avian dinosaurs and birds, but it is not the most recent common ancestor of all birds nor is it a direct ancestor of any species of bird alive today. Rather, it is considered an extinct close evolutionary "cousin" to the direct ancestors.
This may not always be the case, though, as some fossil species are proposed to be directly ancestral to others, like how is most likely to be ancestral to .
Further information: The evolutionary series Appearance Taxa Relationships Status Description Location Image 411 Ma Genus: • The world's oldest known insect. 411 Ma Genus: • Early . 300 Ma Genus: • Ancestral to , and . 316.5 Ma Genus: • A primitive cockroach. 140 Ma Genus: • The earliest known .
92 Ma Genus: • The oldest known species of . This list is ; you can help by . The → Evolutionary Series Appearance Taxa Relationships Status Description Image 523 Ma Genus: • -like in appearance.
Oldest known ancestor of modern Vertebrate characters • Very primitive proto-. 504 Ma Class: • Had fin rays, chevron-shaped and a notochord. 530 Ma Genus: • Appears to have a , thus being a . 480 to 470 Ma Genus: • A well armoured , resembling a large tadpole in life 422–412 Ma Genus: • An , ancestral to the , An unarmored, scaly 419 Ma Genus: • Oldest known This list is ; you can help by .
The Evolutionary Series Appearance Taxa Relationships Status Description Image 420 Ma Genus: • The earliest-known . ??? Ma Genus: • An early relative of the , one eye had already migrated towards the body midline.
48–37 Ma Genus: • The earliest known true 183.7–125.0 Ma Genus: • One of the first . 13 Ma Genus: • One of the oldest known . 13 Ma Genus: • One of the oldest known . 83–70 Ma Genus: • The oldest known fish 56–34 Ma Genus: • A primitive 58–55 Ma Genus: • The oldest known member of the family . 56–34 Ma Genus: • A primitive . 48–37 Ma Genus: • A primitive 58–55 Ma Genus: • A primitive 48–40 Ma Genus: • An early 48–40 Ma Genus: • The oldest known 48–40 Ma Genus: • The oldest known aracanid 48–40 Ma Genus: • A basal 48–40 Ma Genus: • A primitive monodactylid 48–40 Ma Genus: • A primitive monodactylid 48–40 Ma Genus: • A short-snouted ancestor of the modern .
83–65 Ma Genus: • A primitive member of the 83–65 Ma Genus: • A primitive 58–55 Ma Genus: • A primitive member of the 58–55 Ma Genus: • A primitive member of the ???
Ma Genus: • A primitive member of the 65 Ma Genus: • A primitive The → Evolutionary Series Appearance Taxa Relationships Status Description Image 416–359 Ma Genus: • An early member of the , the piscine line leading to tetrapods, is generalised enough to give a fair approximation of the common ancestor of tetrapods and . Fish A small to medium-sized fish with internal nostrils and pectoral fins stiffened by bony components broadly to the and / found in tetrapods.
385 Ma Genus: • Belonging to the family , a that form a sister group to and the tetrapods. Though not on the evolutionary path to tetrapods, Eusthenopteron is of fairly general build and is very well known, serving as an iconic model organism in tetrapod evolution. A medium-sized, mainly fish, mainly use the pectoral and pelvic fins for navigation, and the tail for propulsion. The fin was of diphycercal, foreshadowing the straightening of the spine and the evolution of a contiguous fin in fish like 380 Ma Genus: • Very close to the origin of tetrapods, a "fishapod" .
Fish A large, predatory shallow water fish. As common in shallow water fish, the pectoral and pelvic fins were flexible and paddle-like for propulsion. The dorsal and anal fins are lost, the tail fin contiguous. The were short and wide, indication large amount of oxygen were taken up by the lungs rather than through the gills.
375 Ma Genus: • A "" more tetrapod-like than . A fish, transitional between fish and the early, fish-like . "Fish" with stout, fleshy pectoral fins with a joint between the innermost and the two next bony elements, corresponding to the elbow in higher tetrapods. The bone was free of the skull, functioning as anchoring for the pectoral fins, and at the same time allowing for movement of the neck. 368 Ma Genus: • Analysis of the cranial material shows it was more advanced than , and together with form a sister group to the higher tetrapods.
A fairly fragmentary find, Elginerpeton straddles the fish/tetrapod divide with a mosaic of features resembling , and . Probably one of the "". Though fragmentary, the find includes a shoulder blade (Cleitrum bone) as well as elements of the limbs, which shows it had comparable limbs and , indicating feet rather than fins. 365 Ma Genus: • Known only from fragmentary remains, mostly a lower jaw, Ventastega is morphologically midway between and / . Possibly oldest animal to have feet rather than fins.
A large, dorso-ventrally flattened predatory fish with a well armoured -like skull. While the fins themselves has not been found, the is essentially similar to that of Acanthostega, indicating it too had feet rather than fins. 365 Ma Genus: • Together with the sole early known from fairly complete skeletons. It is the oldest animal known to have feet rather than fins, thus making it a true and the oldest known unquestionable .
First known animal with toes rather than fins. The feet were broad and paddle-like, adapted for movement in water. It retained functional gills in adulthood, behind a fleshy . 365 Ma Genus: • Fairly closely related to . It possibly represent an early (and ultimately unsuccessful) line adapted to moving on land by -like movements. Together with Acanthostega the sole early known from fairly complete skeletons. Early labyrinthodont with , paddle-like feet and reinforced vertebrae and neural spines.
It probably spent time on land, yet retained gills and a tail with . 360 Ma Genus: • While known only from fragmentary remains, it is more advanced than . Early amphibian A large, basically -like creature. The was powerful, indicating it was a competent walker. ??? Ma Genus: • An advanced , it straddle the divide between the fish-like forms and the more advanced amphibians. It has been suggested it is an early .
A large animal with paddle-like six-toed feet. It did however not have gills in adulthood, and is thus the oldest known to depend entirely on breathing with its lungs. 359–345 Ma Genus: • Hailing from the fossil-poor , Pederpes may be ancestral to the higher . Intermediate between the earlier and the later, more advanced labyrinthodonts. Despite an extra toe on the forelimbs, Pederpes had limbs that terminated in feet adapted primarily for walking rather than paddles for combined swimming and walking like the earlier groups.
295 Ma Genus: • The are derived paleozoic amphibians, possibly ancestral to A "classical" , an advanced group. One of the best known , Eryops combines the large, flat skull and short limbs typical of the group.
The → Evolutionary Series Appearance Taxa Relationships Status Description Image 290 Ma Genus: • Colloquially referred to as a "frogamander" due to this taxon being both chronologically and morphologically basal to both and One of the first transitional fossils towards modern amphibians ().
Primitive traits • Backbone with intermediate characteristics • Retains a fully developed tail Derived traits • Bears a large space for a tympanic ear • Ankle bones are fused together like in salamanders • Lightly built wide skull as in frogs 250 Ma Genus: • Intermediate between generalized amphibians and derived frogs Early "almost frog" transitional amphibian Primitive traits • Possessed short limbs and therefore was unable to hop, unlike all extant anurans • Retains fourteen vertebra unlike modern frogs who have four to nine vertebra • Tibia and fibula are not fused into a tibiofibula Derived traits • Skull resembles that of modern skull with a latticework of thin bones in skull 190 Ma Genus: • Another transitional form which could be properly classified as a frog An intermediate form which may replace as the "ultimate" ancestor of anurans Primitive traits • Still possess relatively short limbs Derived traits • Tail is greatly reduced • Does not have greatly enlarged legs, but shows some adaptations for hopping, such as a three-pronged pelvis 213–188 Ma Genus: • A derived fossil frog completing the series of transitional fossils between early amphibians and modern anurans The oldest "true" frog Primitive traits • Retains ten presacral vertebra Derived traits • Hind legs are adapted for hopping 210 Ma Genus: • Intermediate between basal amphibians and An early Primitive traits • Bears three-toed vestigial limbs • The size of the orbits indicates well developed eyes and suggest a non-subterranean lifestyle Derived traits • The body has been adapted to a sort of serpentine shape The → Evolutionary Series Appearance Taxa Relationships Status Description Image 326–318 Ma Genus: • One of the early amphibians Amphibian A large, somewhat lizard-like with a deep skull, laterally placed eyes and five digits to each foot.
??? Ma Genus: • The order is the sister group of the . The Limnoscelis was originally described as a "" (early reptiles) together with the other . Today the large-bodied diadectomorphs are thought to have had a larval stage, falling close to, but just outside the amphibian/reptile divide.
A large, predatory reptile-like amphibian. The limbs are extremely heavily built, indicating it fed on slow moving prey. ??? Ma Genus: • Uncertain phylogeny, possibly a or Amphibian A medium-sized, probably herbivorous animal 350 Ma Genus: • Uncertain phylogenetic position. Westlothiana may be a small-bodied , falling just outside the amphibian/reptile divide Originally described as the first , it is now considered an advanced . Small, probably insectovorious animal.
The body and tail was long, the limbs small, somewhat like a modern . 320–305 Ma Genus: • Possibly allied to the , or belonging to a sister group to Diadectomorpha and Amniota Likely an amphibian Smallish, likely carnivorous. 340 Ma Genus: • The fragmentary nature of the fossil (it lacks a ) makes an exact phylogenetic position hard to establish. Possibly the first animal with an egg, and thus the first amniote and thus the latest common ancestor to both and . Small lizard-like animal, the first known to possess , indicating it has amniote type skin with .
315 Ma Genus: • One of several small, basal reptile genera Reptile once thought to be the common ancestor of both and sauropsids, Hylonomus is now considered a eureptilan creature nested inside . 312–304 Ma Genus: • One of several small, basal reptile genera Reptile (most likely a ) An early reptile. In phylogenetic analysis it falls on the side, it is thus likely a progenitor of the The → Evolutionary Series Appearance Taxa Relationships Status Description Image 120 Ma Genus: • A Basal snake with 4 limbs.
95 Ma Genus: • A basal snake with two hind-limbs. 92 Ma Genus: • A transitional form between and limbless snakes retaining distinct, if non-functional, legs. 90 Ma Genus: • A basal snake with two hind-limbs. This list is ; you can help by . The → series Appearance Taxa Relationships Status Description Image ??? Ma Genus: • The oldest known archosaur, Archosaurus was one of the largest land reptiles during the , about the size of to today's .
It looked somewhat -like, with sprawling legs, long jaws, powerful neck muscles and a long tail. A distinct proterosuchid trait is the peculiar hook-shaped mouth. ??? Ma Genus: • ??? Ma Genus: • The oldest known animal on the / side of the archosaurian tree (the ), dating to about 245 million years ago.
A small, lightly built animal. It had a fairly long neck (contrary to the short necked relatives of ), but ran on all four legs.
??? Ma Genus: • Known from a somewhat fragmentary find, Spondylosoma was possibly an early dinosaur, or near dinosaur. It has however also been classified as a . 228 Ma Genus: • A very early representative of the stem line or perhaps even the as a whole.
A small (1 meter, ~ 10 kg) bipedal carnivore with numerous sharp teeth. It was a swift runner. The forelimbs were half the length of the hindlimbs and the hands had five fingers This list is ; you can help by . The evolutionary series Appearance Taxa Relationships Status Description Image 228 to 216.5 Ma Genus: • The oldest known .
216–200 Ma Genus: • The most primitive well-known representative of the dinosaurs. 160 Ma Genus: • The oldest and most primitive known . 90 Ma Genus: • A basal from the late . 160 Ma Genus: • A genus of basal dinosaur from the Period of central Asia. 160 Ma Genus: • A genus of dinosaur, one of the earliest known examples of the lineage. 126 Ma Genus: • An early genus of 208–194 Ma Genus: • One of the most primitive . 95 Ma Genus: • A possible ancestor of the .
120 Ma Genus: • A primitive (basal) . Further information: The → Evolutionary Series Appearance Taxa Relationships Status Description Image 152–151 Ma Genus: • Primitive traits • Undifferentiated hind digits displaying no specialties for climbing • Spine attaches to the back end of the skull rather than the base • Moderately long, bony tail Derived traits • Basic proto-feathers cover parts of the body for insulation 168–152 Ma Genus: • The find is represented only by a hind leg, but one that is very bird-like.
It belonged to a small dinosaur with long, pennaceous feathers on its hind legs and (in all likelihood) arms. 161–151 Ma Genus: • Basal Although once classified as a bird, Anchiornis is now considered a basal which bears pennaceous, symmetrical feathers on all four limbs.
Primitive traits • Wings symmetrical and rounded, probably not used for flight but instead insulation, mating displays, and gliding • Long legs overall morphology similar to that of other • Spine attaches to the back end of the skull rather than the base • Moderately long, bony tail Derived traits • Flexible wrists which are more similar to aves than other theropods • Like birds and unlike troodontids, Anchiornis had arms nearly the same length as the hind legs • Bore primary and secondary pennaceous symmetrical wings on both arms, legs, toes, and wrist 150–145 Ma Genus: • Known for its mosaic of avian and theropod characteristics is both the first primitive bird in the fossil record and one of the first discovered.
Traditionally seen as the first proper bird, though it is not directly ancestral to modern birds. An excellent intermediate form between dinosaurs and birds.
Capable of gliding, but lacking and , it could likely not sustain powered flight. Primitive traits • Slower dinosaur-like growth rate • No • Spine attaches to the back end of the skull rather than the base • Forelimbs have three unfused, clawed fingers, no • Maxilla and premaxilla bore unserrated teeth • Moderately long, bony tail Derived traits • Fully developed asymmetrical flight feathers • Fused from two joined clavicles • Backward and elongated pubis similar to maniraptors, but not found in more primitive theropods 120 Ma Genus: • Found in the famous Confuciusornis is the first primitive bird with a .
With its short tail and toothless beak, Confuciusornis is very modern looking compared to . The toothless beak is however a case of , as more advanced birds retained teeth, illustration the sometimes confusing of the dinosaur-bird transition. Primitive traits • Retained unfused clawed digits, no • Sideways-facing glenoid joint Derived traits • Short tail with fused vertebrae at the end () • Larger sternum with a low primitive • Unlike other early birds Confuciusornis had a toothless beak 115 Ma Genus: • Primitive bird and possibly a descendant of "urvogels" like Archaeopteryx.
First bird to possess an . Plesiomophic traits • Two unfused, functional digits remain on second and third digit Derived traits • First digit bearing an rather than claw 93.5–75 Ma Genus: • Considered a close relative to the ancestor to modern birds A flying bird found in several epochs in the late Cretaceous which still bore teeth, but in most respects very similar to .
Primitive traits • Numerous sharp teeth in much of the beak Derived traits • Fused bones () II & III of the hand • Rigid ribcage with a well-developed • No functional on the hand • Short childhood with distinct adult stage.
Further information: The → Evolutionary Series Appearance Taxa Relationships Status Description Image ??? Ma Genus: • Known from very fragmentary finds, Protoclepsydrops may be the earliest (mammal-like reptile) A low-slung, lizard-like animal of moderate size.
306 Ma Genus: • The oldest undisputed (mammal-like reptile) Primitive traits • A relatively flat, reptile-like skull • Typically reptilian sprawling gait • Generally lizard-like proportions with a flattened body Derived traits • Temporal opening low on the side of the , between the and the elements above.
• Tendency to enlarged forward teeth on the 297 Ma Genus: • A primitive member of the , or possibly just outside the group. A -grade synapsid Derived traits • Two or three moderately large canine-like teeth about a third down the .
• bone the largest element of the lower jaw • The skull deeper than in 265 Ma Genus: • An advanced member of the family , from which the (advanced synapsids) evolved A -grade synapsid. At up to 4 meters, Dimetrodon was one of the largest animals of its time. The distinct sail of the back makes it the most recognized synapsid known Primitive traits • Cold blooded metabolism dependent of external heat source (hence the "sail") • Sprawling gait • No secondary palate • No enlarged side teeth in the lower jaw Derived traits • Distinctly elongated 2nd and 3rd tooth on the , corresponding to the in mammals.
The first canine generally longer than the second. • Skull deep and narrow • Body overall deeper than in earlier forms 267 Ma Genus: • A primitive . About the size of a large dog, Biarmosuchus was a lightly built and likely fairly agile animal for its size. Primitive traits • No indicate limited overall oxygen consumption and hence metabolism • Sprawling legs, but the legs longer and more slender than in pelycosaurs • Long -like tail Derived traits • A single canine as the first tooth on the , all other maxillary teeth small • Tendency for an enlarged caninelike tooth on the • Internal nostrils covered by a partial fleshy • Enlarged temporal opening giving more powerful bite 247–237 Ma Genus: • An advanced synapsid All species of Cynognathus were rather heavyset carnivores about a meter in length and with a sprawling gait and heavy jaws.
Primitive traits • No bony palate • No differentiated cheek teeth Derived traits • Teeth clearly differentiated into , and cheek teeth in both upper and lower jaws • Cheek teeth with multiple cusps 248–245 Ma Genus: • A small bodied relative of the larger .
An advanced , just on the reptilian side of the reptile/mammal divide. Ranging from badger to marten-sized, it was a burrower of very mammal-like habit. Primitive traits • While the dominated the lower jaw, the hinge was between the and . • Teeth even at very young age with no , indicating no or limited and hence slow growth. • No , indicating lack of fur and hence limited enothermy. May have had Derived traits • Well developed respiratory turbinates and palate, indicating • Generally mammal-like dentition.
• Mammal-like ecology: burrowing and small size • Animals of different sizes found together, indicating post-hatching . 205 Ma Genus: • A smaller, more shrew-like relative of and An early mammal, possibly representing the earliest lactating animals, but outside the (a ) primitive traits • Semi-sprawling gait • and still forming a small jaw articulation, though main joint being the between the and • Large number of teeth Advanced traits • Only two sets of teeth with full .
No teeth in infancy, indication • Short mammalian-type lifespan • Presence of , indication and hence endothermy 125 Ma Genus: • One of the An early mammal. Primitive traits • Long body with 26 and (only 20 in modern mammals) • Lumbar vertebrae with • and still attached to lower jaw via (the evolution of the ammalian have taken place separately in and ) Advanced traits • Small, very lightly built • Borrowing • Insectivorious Further information: The Evolutionary Series Appearance Taxa Relationships Status Description Image 100–104 Ma Genus: • The earliest known .
125 Ma Genus: • The oldest known. ?? Ma Genus: • The earliest-known . 164–165 Ma Genus: • The oldest known 63-50 Ma Genus: • The earliest known . 60–55 Ma Genus: • The possible ancestor of the modern order . 15.97–11.61 Ma Genus: • The earliest known .
20–18 Ma Genus: • The earliest known . 45–40 Ma Genus: • The oldest known, it was also the smallest. ??? Ma Genus: • Suspected to be the ancestor of modern and .
55.4–48.6 Ma Genus: • Suspected to be the ancestor of modern . 38–33.9 Ma Genus: • The earliest known . ??? Ma Genus: • The earliest known . 52.5 Ma Genus: • One of the two oldest known genera of . 2 Ma Species: • The earliest known member of the clade. 63–61.7Ma Genus: • Believed to be the earliest example of a or a proto-primate, a primatomorph precursor to the . 12.5–8.5 Ma Genus: • This genus may have been the ancestor to the modern . 16–8 Ma Genus: • A possible ancestor of living . ??
Ma Genus: • The earliest known true (and scaled) . Further information: The Evolutionary Series Appearance Taxa Relationships Status Description Image 36–32 Ma Genus • The oldest primitive monkey known in the fossil record, dating back before the split between Old and New World monkeys.
Basal to both Old and New World monkeys. Primitive traits • Smaller canines than later monkeys such as • Retains some post-cranial characters seen in prosimians Derived traits • Fused mandibular symphysis • Scapula similar to modern squirrel monkeys • Low rounded molar cusps rather than high cusps as is seen in and 33 Ma Genus • A Miocene monkey which bridges the gap between the Eocene ancestors of and Miocene ancestor of .
Tentatively positioned transitional form prior to the Old World monkey/ape split. Primitive traits • Retained auditory features similar to Old World monkeys • Incapable of true unlike extant apes • Reduced capitular tail, but was proportionally smaller than Derived traits • Ape-like teeth including broad, flat incisors and sexually dimorphic canines • A low sagittal keel and strong temporalis muscles • Increased size in the visual cortex 27–14 Ma Genus • This primate exhibits very ape-like features like its teeth, but much of its post-cranial remains are more similar to monkeys.
Universally accepted to be intermediate between 'ape-like monkeys' such as Aegyptopithecus and later apes including hominids. Primitive traits • Monkey-like wrist • Narrow, monkey-like Derived traits • Completely lacked a fully formed tail • 5-Y pattern on lower molar cusps as also seen in hominoids 13 Ma Genus: • A European ape which is considered to be the predecessor of the great apes.
Some objections have been raised to this fossils status due to its location in Spain, but Pierolapithecus is likely a transitional taxon between generalized apes and the lineage which led to great apes. Pleisomorphic traits • Relatively short fingers and walked in a similar quadrupedal fashion like baboons • Lacks adaptations for both gibbon-style brachaition as well as derived knuckle-walking like in chimpanzee's and gorilla's Derived traits • Flat, wider rib cage like great apes for tree-climbing • The clavicle is large and similar to modern chimps suggesting a dorsally positioned scapula 4.4 Ma Genus: • A woodland hominid adapted to quadruped arboreal locomotion, but also for bipedalism.
Intermediate between the last common ancestor of chimps and humans, and the . Primitive traits • Brains smaller than later hominids ranging from about 300-350 cc • Foot thumb is not retracted into the foot as a • Phalanges are more heavily curved than in Derived traits • Reduced size in canines, however still retained dimorphic characters • Hind leg dominant, bipedal locomotion while walking, however were quadrupedal while climbing trees 4.4–2.0 Ma Genus: • First known genus of fully bipedal apes which are probably ancestral to and the genus .
Intermediate between extinct quadrupedal and bipedal apes. While the relationship between some species are being revised, is considered to be, by most experts, the ancestor to all later hominids.
Primitive traits • Some species retain a • Curved phalanges, indicating semi-arboreal lifestyle • Semisectorial premolar is present • Prognathic face to varying degrees Derived traits • Fully bipedal as indicated by many features including the knee joint, hips, lumbar curve in the spine, position of the , and feet • Increase in brain size ranging from about 375-500 cc • Development of a parabolic jaw 2.3–1.4 Ma Species: • An early human which is the morphological link between and later human species.
Perfect intermediate between early hominids and later humans, possibly ancestral to modern humans. Primitive traits • Pronounced brow ridge • Foramen magnum is not positioned as anteriorly like in modern humans, giving a slightly semi-erect appearance • Although reduced in size the teeth are still fairly large Derived traits • Increase brain size ranging from 510-800 cc • Face is slightly prognathic, but at a much steeper angle • Bulge in the Broca area, possibly the first hominid to use rudimentary speech • Associated with the first use of stone tools 2.0–1.0 Ma Species: • Very successful hominid, which was probably ancestral to both modern and .
Probably the first hominid to leave and successfully colonize territories outside of Africa. Ancestral to modern humans and neanderthals. Primitive traits • Still retains a heavy brow ridge and • Lacked the complexity of modern human language, but does show increase in the Broca area • Thicker bones and larger teeth than modern humans Derived traits • Rounder and larger brain (about 900–1,100 cc) than H.
habilis • Face is orthognathic compared to H. habilis • Probably lived in and was an active group hunter • Associated with advanced stone tools and possibly the first hominid to use and produce fire 500 Ka–recent Species • Homo rhodesiensis was the immediate ancestor of modern humans which evidently displaced the in Europe and the island of southeast Asia.
H. rhodesiensis evolved from about half a million years ago but still retains some primitive characteristics such as relatively thick bones and molars larger than modern humans. Ancestral to modern humans. Primitive traits • Large teeth • Heavy brow ridge • Extremely robust build in most groups Derived traits • Rounder, less broad based cranium • Larger brain size, approaching (and sometimes exceeding) modern values • Stauffer, RC (1975) Charles Darwin's Natural Selection; being the second part of his big species book written from 1856 to 1858.
Cambridge: Cambridge University Press. p. 236. • Darwin, C. R. 1859. On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. London: John Murray. p. 187. • Delezene, LK; Kimbel, WH (2011). "Evolution of the mandibular third premolar crown in early Australopithecus". Journal of Human Evolution. 60 (6): 711–730. :. . • Shu, D.
G.; Morris, S. C.; Han, J.; Zhang, Z. F.; Yasui, K.; Janvier, P.; Chen, L.; Zhang, X. L.; Liu, J. N.; Li, Y.; Liu, H. -Q. (2003), , Nature, 421 (6922): 526–529, :, :, • Ahlberg, Per Erik (2001). . Washington, DC: Taylor & Francis. p. 188. . • Zhu, M.; Zhao, W.; Jia, L.; Lu, J.; Qiao, T.; Qu, Q. (2009). "The oldest articulated osteichthyan reveals mosaic gnathostome characters". . 458 (7237): 469–474. :. :. . • ^ Ahlberg, P. E.; Johanson, Z. (1998). (PDF). Nature.
395 (6704): 792–794. :. :. • ^ R. Cloutier (1996). "Taxonomic review of Eusthenopteron foordi.". Devonian Fishes and Plants of Miguasha, Quebec, Canada. Dr. Friedrich Pfeil, München. pp. 487–502. • Nature: • (1995). "Between fish and amphibians". Nature. 373 (6513): 389–390. :. :. • Brazeau, M.D.; Ahlberg, P.E. (2006). "Tetrapod-like middle ear architecture in a Devonian fish".
. 439 (7074): 318–321. :. :. . • John Noble Wilford, The New York Times, , 5 April 2006. • ^ Shubin, Neil (2008). Your Inner Fish. Pantheon. . • . New Scientist Magazine . Retrieved 2007-02-07. • ^ Ahlberg, Per E. (1995).
"Elginerpeton pancheni and the earliest tetrapod clade". Nature. 373 (6513): 420–425. :. :. • at 18 January 2010 at • ^ Ahlberg, Per. E.; ; Ervins Luksevics; Henning Blom; Ivars Zupins (26 June 2008). . . 453 (7199): 1199–1204. :. :. . • (2005-11-21). . Scientific American. Archived from on 2006-11-04. • "," Devonian Times. 17 January 2010 at • (2009). Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body.
New York: Vintage. p. 13. . • Lebedev, O.A. (1984). "The first find of a Devonian tetrapod vertebrate in the USSR". Doklady Akademii Nauk SSSR. Palaeontology (in Russian). 278: 1470–1473. • Gordon, M.S.; Long, J.A. (2004). (PDF). Physiological and Biochemical Zoology. 77 (5): 700–719. :. . • Clack, J. A. (2002). "An early tetrapod from 'Romer's Gap '". Nature. 418 (6893): 72–76. :. . • ^ Anderson, J. S.; Reisz, R. R.; Scott, D.; Fröbisch, N.
B.; Sumida, S. S. (2008). "A stem batrachian from the Early Permian of Texas and the origin of frogs and salamanders". . 453 (7194): 515–518. :. :. . • Estes, R., and O. A. Reig. (1973): "The early fossil record of frogs: a review of the evidence." Pp. 11–63 In J. L. Vial (Ed.), Evolutionary Biology of the Anurans: Contemporary Research on Major Problems. University of Missouri Press, Columbia.
• Moss J.L. (1972). "The Morphology and phylogenetic relationship of the Lower Permian tetrapod Tseajaia campi Vaughn (Amphibia: Seymouriamorpha)". University of California Publications in Geological Sciences. 98: 1–72. • Berman, D.S.; Sumida, S.S.; Lombard, R.E.
(1992). "Reinterpretation of the temporal and occipital regions in Diadectes and the relationship of diadectomorphs". . 66: 481–499. • ^ Gauthier J., Kluge, A.G., & Rowe, T. (1988) "The early evolution of the Amniota." In: M. J. Benton (ed.) The Phylogeny and Classification of the Tetrapods, Volume 1: Amphibians, Reptiles, Birds (1): pp 103–155. Oxford: Clarendon Press.
• on the • R. L. Paton, T. R. Smithson and J. A. Clack, "An amniote-like skeleton from the Early Carboniferous of Scotland", , Nature 398, 508–513 (8 April 1999) • . 2008-04-10 . Retrieved 2008-04-16. • • • Nesbitt, S.J.; ; Irmis, R.B.; Angielczyk, K.D.; Smith, R.M.H.; Tsuji, L.M.A.
(2010). "Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira". Nature. 464 (7285): 95–98. :. :. . • Langer, M.C.
(2004). Basal Saurischia. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (second edition). University of California Press:Berkeley, 25-46. • Galton, P.M. (2000). "Are Spondylosoma and Staurikosaurus (Santa Maria Formation, Middle-Upper Triassic, Brasil) the oldest saurischian dinosaurs?".
Paläontologische Zeitschrift. 74 (3): 393–423. :. • R.N. Martinez et al. A basal dinosaur from the dawn of the dinosaur era in southwestern Pangaea. Science, Vol. 331, 14 January 2011, p. 206. • Kaplan M, , , 13-1-2011. • Apaldetti, C; Martinez, RN; Alcober, OA; Pol, D (2011). "A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina". PLoS ONE. 6 (11): e26964. : (inactive 2018-11-19).
• Padian, K. & Chiappe, L.M. (1997): Bird Origins. In: Encyclopedia of Dinosaurs (red. Currie, P.J & Padian, K., , , pp 41–96, • Chinsamy A.; Martin L.D.; Dobson P. (1998). "Bone microstructure of the diving Hesperornis and the volant Ichthyornis from the Niobrara Chalk of western Kansas". Cretaceous Research. 19 (2): 225–235. :. • Jörg Fröbisch, Rainer R.
Schoch, Johannes Müller, Thomas Schindler and Dieter Schweiss (2011). (PDF). Acta Palaeontologica Polonica. 56 (1): 113–120. :. CS1 maint: Uses authors parameter () • ^ Michel Laurin (1994).
. Journal of Vertebrate Paleontology. 14 (1): 134–138. :. CS1 maint: Uses authors parameter () • Romer, A.S.; Price, L.L. (1940). "Review of the Pelycosauria". Special Papers of the Geological Society of America. Geological Society of America Special Papers. 28: 1–538. :. • GA Floridesa, Kalogiroua SA; SA; Wrobelb, L Tassoub (2001). "Natural environment and thermal behavior of Dimetrodon limbatus". Journal of Thermal Biology.
26 (1): 15–20. :. . • Angielczyk, Kenneth D. (June 2009). . Evolution: Education and Outreach. 2 (2): 257–271. :. • ^ White, T. & Kazlev, M. A. (2009): , from website. • Ruben, J.A.; Hillenius, W.J.; Kemp, T.S.; Quick, D.E. (2011). . In Chinsamy-Turan, A. (ed.). Forerunners of Mammals. Bloomington: Indiana University Press. pp. 272–286. . CS1 maint: Uses editors parameter () • Maier, W.; Heever, J.; Durand, F.
(27 April 2009). "New therapsid specimens and the origin of the secondary hard and soft palate of mammals". Journal of Zoological Systematics and Evolutionary Research. 34 (1): 9–19. :. • Czaplewski, Terry A. Vaughan, James M. Ryan, Nicholas J. (2000). (4th ed.). Fort Worth: Brooks/Cole Thomson Learning. p. 51. . • Ruben, J. A. (1 August 2000). "Selective Factors Associated with the Origin of Fur and Feathers". Integrative and Comparative Biology. 40 (4): 585–596. :.
• . National Science Foundation. March 14, 2007. • Zhe-Xi Luo, Chong-Xi Yuan, Qing-Jin Meng and Qiang Ji (25 August 2011). . Nature. 476 (7361): 442–445. :. :. . CS1 maint: Uses authors parameter ()
best dating of fossil wikipedia - Fossil Dating Site, 100% Free Online Dating in Fossil, OR
Wikipedia Wikipedia is a collaboratively developed, free content encyclopedia. It is very similar to , although it is a general knowledge encyclopedia, rather than being specific to one topic (as this wiki is specific). Because of this, it is not always particularly friendly to in-depth knowledge specific to some topics. Wikipedia could be viewed as a "mother project" of sorts to Fossil Wiki—while there is no official relationship, it is doubtful that this site would ever have existed without the inspiration of Fossil Wiki.
Wikipedia is a wiki that has general information on anything legitimate; in addition, there are also smaller wikis, like Fossil Wiki, that are devoted to specific topics.
It should also be noted that Fossil Wiki was created entirely independently of The Wikimedia Foundation and of any events occurring on Wikipedia, though many Fossil Wikians are also Wikipedians, and much information is shared between the two projects.
So, how do we know how old a fossil is? There are two main methods determining a age, relative dating and absolute dating. Relative dating is used to determine a fossils approximate age by comparing it to similar rocks and fossils of known ages. Absolute dating is used to determine a precise age of a fossil by using radiometric dating to measure the decay of isotopes, either within the fossil or more often the rocks associated with it.
The majority of the time fossils are dated using relative dating techniques. Using relative dating the fossil is compared to something for which an age is already known. For example if you have a and it was found in the Wheeler Formation. The Wheeler Formation has been previously dated to approximately 507 million year old, so we know the trilobite is also about 507 million years old.
But, how can we determine how old a rock formation is, if it hasn’t previously been dated? Scientists can use certain types of fossils referred to as to assist in relative dating via correlation.
Index fossils are fossils that are known to only occur within a very specific age range. Typically commonly occurring fossils that had a widespread geographic distribution such as brachiopods, trilobites, and ammonites work best as index fossils. If the fossil you are trying to date occurs alongside one of these index fossils, then the fossil you are dating must fall into the age range of the index fossil.
Sometimes multiple index fossils can be used. In a hypothetical example, a rock formation contains fossils of a type of brachiopod known to occur between 410 and 420 million years. The same rock formation also contains a type of trilobite that was known to live 415 to 425 million years ago.
Since the rock formation contains both types of fossils the ago of the rock formation must be in the overlapping date range of 415 to 420 million years. Studying the layers of rock or strata can also be useful. Layers of rock are deposited sequentially.
If a layer of rock containing the fossil is higher up in the sequence that another layer, you know that layer must be younger in age. If it is lower in sequence it’s of a younger age. This can often be complicated by the fact that geological forces can cause faulting and tilting of rocks.
Absolute dating is used to determine a precise age of a rock or fossil through methods. This uses radioactive minerals that occur in rocks and fossils almost like a geological clock.
It’s often much easier to date volcanic rocks than the fossils themselves or the sedimentary rocks they are found in. So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks. The atoms in some chemical elements have different forms, called isotopes. These isotopes break down at a constant rate over time through radioactive decay.
By measuring the ratio of the amount of the original (parent) isotope to the amount of the (daughter) isotopes that it breaks down into an age can be determined. We define the rate of this radioactive decay in half-lives. If a radioactive isotope is said to have a half-life of 5,000 years that means after 5,000 years exactly half of it will have decayed from the parent isotope into the daughter isotopes.
Then after another 5,000 years half of the remaining parent isotope will have decayed. While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils. Carbon-14, the radioactive isotope of carbon used in carbon dating has a half-life of 5730 years, so it decays too fast. It can only be used to date fossils younger than about 75,000 years. Potassium-40 on the other hand has a half like of 1.25 billion years and is common in rocks and minerals.
This makes it ideal for dating much older rocks and fossils.
ESS1C - The History of the Earth