Vertebrate paleontology is a large subfield to paleontology

Paleontology

Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...

 seeking to discover the behavior, reproduction and appearance of extinct animals with vertebrae or a notochord

Notochord

The notochord is a flexible, rod-shaped body found in embryos of all chordates. It is composed of cells derived from the mesoderm and defines the primitive axis of the embryo. In some chordates, it persists throughout life as the main axial support of the body, while in most vertebrates it becomes...

, through the study of their fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

ized remains. It also tries to connect, by using the evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

ary timeline

Timeline of evolution

This timeline of evolution of life outlines the major events in the development of life on planet Earth since it first originated until the present day. In biology, evolution is any change across successive generations in the heritable characteristics of biological populations...

, the animals of the past and their modern-day relatives.

The fossil record shows aspects of the meandering evolutionary path from early aquatic vertebrate

Vertebrate

Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s to mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, with a host of transitional fossil

Transitional fossil

A transitional fossil is any fossilized remains of a lifeform that exhibits characteristics of two distinct taxonomic groups. A transitional fossil is the fossil of an organism near the branching point where major individual lineages diverge...

s, though there are still large blank areas. The earliest known fossil vertebrates were heavily armored fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 discovered in rocks from the Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

 Period about 500 to 430 Ma (megaannum, million years ago). The Devonian

Devonian

The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

 Period (395 to 345 Ma) brought in the changes that allowed primitive air-breathing fish to remain on land as long as they wished, thus becoming the first terrestrial vertebrates, the amphibian

Amphibian

Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s.

Amphibians developed forms of reproduction and locomotion and a metabolism

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 better suited for life exclusively on land, becoming more reptilian

Reptile

Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...

. Full fledged reptiles appeared in the Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

 Period (345 to 280 Ma).

The reptilian changes and adaptations to diet and geography are chronicled in the fossil record of the varying forms of therapsida

Therapsida

Therapsida is a group of the most advanced synapsids, and include the ancestors of mammals. Many of the traits today seen as unique to mammals had their origin within early therapsids, including hair, lactation, and an erect posture. The earliest fossil attributed to Therapsida is believed to be...

. True mammals showed up in the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Period (225 to 190 Ma) around the same time as the dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s, which also sprouted from the reptilian line.

Bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s first diverged from dinosaurs between 100 Ma and 60 Ma.

History

One of the people who helped figure out the vertebrate progression was French zoologist Georges Cuvier

Georges Cuvier

Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...

 (1769–1832), who realized that fossils found in older rock strata differed greatly from more recent fossils or modern animals. He published his findings in 1812 and, although he steadfastly refuted evolution

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

, his work proved the (at the time) contested theory of extinction

Extinction

In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 of species.

Thomas Jefferson

Thomas Jefferson

Thomas Jefferson was the principal author of the United States Declaration of Independence and the Statute of Virginia for Religious Freedom , the third President of the United States and founder of the University of Virginia...

 is credited with initiating the science of vertebrate paleontology in the United States with the reading of a paper to the American Philosophical Society

American Philosophical Society

The American Philosophical Society, founded in 1743, and located in Philadelphia, Pa., is an eminent scholarly organization of international reputation, that promotes useful knowledge in the sciences and humanities through excellence in scholarly research, professional meetings, publications,...

 in Philadelphia in 1797. Jefferson presented fossil bones of a ground sloth found in a cave in western Virginia and named the genus (Megalonyx

Megalonyx

Megalonyx is an extinct genus of giant ground sloths of the family Megalonychidae endemic to North America from the Hemphillian of the Late Miocene through to the Rancholabrean of the Pleistocene, living from ~10.3 Mya—11,000 years ago, existing for approximately .-Taxonomy:The generic name...

). The species was ultimately named Megalonyx jeffersonii in his honor. Jefferson corresponded with Cuvier, including sending him a shipment of highly desirable bones of the American mastodon

American mastodon

The American mastodon is an extinct North American proboscidean that lived from about 3.7 million years ago until about 10,000 BC. It was the last surviving member of the mastodon family. Fossil finds range from present-day Alaska and New England in the north, to Florida, southern...

 and the woolly mammoth

Woolly mammoth

The woolly mammoth , also called the tundra mammoth, is a species of mammoth. This animal is known from bones and frozen carcasses from northern North America and northern Eurasia with the best preserved carcasses in Siberia...

.

Paleontology really got started though, with the publication of Recherches sur les poissons fossils (1833–1843) by Swiss naturalist Louis Agassiz

Louis Agassiz

Jean Louis Rodolphe Agassiz was a Swiss paleontologist, glaciologist, geologist and a prominent innovator in the study of the Earth's natural history. He grew up in Switzerland and became a professor of natural history at University of Neuchâtel...

 (1807–1873). He studied, described and listed hundreds of species of fossil fish, beginning the serious study into the lives of extinct animals. With the publication of the Origin of Species by Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

 in 1849, the field got a theoretical framework. Much of the subsequent work has been to map the relationship between fossil and extant organisms, as well at their history through time.

In modern times, Alfred Romer

Alfred Romer

Alfred Sherwood Romer was an American paleontologist and comparative anatomist and a specialist in vertebrate evolution.-Biography:...

 (1894–1973) wrote what has been termed the definitive textbook on the subject, called Vertebrate Paleontology

Vertebrate Paleontology (Romer)

Vertebrate Paleontology is an advanced textbook on vertebrate paleontology by Alfred Sherwood Romer, published by the University of Chicago Press. It went through three editions and for many years constituted a very authoritative work and the definitive coverage of the subject. A condensed...

. It shows shows the progression of evolution in fossil fish, and amphibians and reptiles through comparative anatomy, including a list of all the (then) known fossil vertebrate genera. Romer became the first president of the Society of Vertebrate Paleontology

Society of Vertebrate Paleontology

The Society of Vertebrate Paleontology was founded in 1940 for individuals with an interest in vertebrate paleontology. SVP now has almost 2,000 members. The society's website states that SVP "is organized exclusively for educational and scientific purposes...

 in 1940, alongside co-founder Howard Chiu. An updated work that largely carried on the tradition from Romer, and by many considered definitive book on the subject was written by Robert L. Carroll

Robert L. Carroll

Robert Lynn Carroll is a vertebrate paleontologist who specialises in Paleozoic and Mesozoic amphibians and reptiles.Carroll was an only child and grew up on a farm near Lansing, Michigan...

 of McGill University, the 1988 text Vertebrate Paleontology and Evolution. Carroll was president of the Society of Vertebrate Paleontology in 1983. The Society keeps its members informed on the latest discoveries through newsletters and the Journal of Vertebrate Paleontology.

Paleontological Vertebrate Classification

The 'traditional' vertebrate classification scheme employ evolutionary taxonomy

Evolutionary taxonomy

Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship and overall similarity. This type of taxonomy considers taxa rather than single species, so that...

 where several of the taxa listed are paraphyletic, i.e. have given rise to another taxa that have been given the same rank. For instance, bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s are generally considered to be the descendants of Reptiles (Saurischian dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s to be precise), but in this system both are listed as separate classes. Under phylogenetic nomenclature

Phylogenetic nomenclature

Phylogenetic nomenclature or phylogenetic taxonomy is an alternative to rank-based nomenclature, applying definitions from cladistics . Its two defining features are the use of phylogenetic definitions of biological taxon names, and the lack of obligatory ranks...

, such an arrangement is unacceptable, though it offers excellent overview.

This classical scheme is still used in works where systematic overview is essential, e.g. Benton

Michael Benton

Michael J. Benton is a British paleontologist, a Fellow of the Royal Society of Edinburgh, and professor of vertebrate palaeontology in the Department of Earth Sciences at the University of Bristol....

 (1998), Hildebrand and Goslow (2001) and Knobill and Neill (2006). While mostly seen in general works, it is also still used in some specialist works like Fortuny & al. (2011).

(For an alternative system see List of dinosaur classifications.)

Kingdom Animalia

• Phylum Chordata (vertebrates)
  • Class Agnatha
    Agnatha
    Agnatha is a superclass of jawless fish in the phylum Chordata, subphylum Vertebrata. The group excludes all vertebrates with jaws, known as gnathostomes....
    
     (jawless fish)
    • Subclass Cyclostomata
      Cyclostomata
      Cyclostomata is a group of chordates that comprises the living jawless fishes: the lampreys and hagfishes. Both groups have round mouths that lack jaws but have retractable horny teeth...
      
       (hagfish
      Hagfish
      Hagfish, the clade Myxini , are eel-shaped slime-producing marine animals . They are the only living animals that have a skull but not a vertebral column. Along with lampreys, hagfish are jawless and are living fossils whose next nearest relatives include all vertebrates...
      
       and lamprey
      Lamprey
      Lampreys are a family of jawless fish, whose adults are characterized by a toothed, funnel-like sucking mouth. Translated from an admixture of Latin and Greek, lamprey means stone lickers...
      
      s)
    • Subclass Ostracodermi (armoured jawless fish) †
  • Class Chondrichthyes
    Chondrichthyes
    Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...
    
     (cartilaginous fish)
    • Subclass Elasmobranchii
      Elasmobranchii
      Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, that includes the sharks and the rays and skates .-Evolution:...
      
       (shark
      Shark
      Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
      
      s and rayes
      Batoidea
      Batoidea is a superorder of cartilaginous fish commonly known as rays and skates, containing more than 500 described species in thirteen families...
      
      )
    • Subclass Holocephali
      Holocephali
      The subclass Holocephali is a taxon of cartilaginous fish, of which the order Chimaeriformes is the only surviving group.Holocephali has an extensive fossil record that starts during the Devonian period. However, most fossils are teeth, and the body forms of numerous species are not known, or, at...
      
       (chimaera
      Chimaera
      Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish , spookfish , or rabbitfishes...
      
      s and extinct relatives)
  • Class Placodermi
    Placodermi
    Placodermi is a class of armoured prehistoric fish, known from fossils, which lived from the late Silurian to the end of the Devonian Period. Their head and thorax were covered by articulated armoured plates and the rest of the body was scaled or naked, depending on the species. Placoderms were...
    
     (armoured fish) †
  • Class Acanthodii
    Acanthodii
    Acanthodii is a class of extinct fishes, sharing features with both bony fish and cartilaginous fish. In form they resembled sharks, but their epidermis was covered with tiny rhomboid platelets like the scales of holosteans...
    
     ("spiny sharks", sometimes classified under bony fishes) †
  • Class Osteichthyes
    Osteichthyes
    Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...
    
     (bony fish)
    • Subclass Actinopterygii
      Actinopterygii
      The Actinopterygii or ray-finned fishes constitute a class or sub-class of the bony fishes.The ray-finned fishes are so called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines , as opposed to the fleshy, lobed fins that characterize...
      
      
    • Subclass Sarcopterygii
      Sarcopterygii
      The Sarcopterygii or lobe-finned fishes – sometimes considered synonymous with Crossopterygii constitute a clade of the bony fishes, though a strict classification would include the terrestrial vertebrates...
      
      
  • Class Amphibia
    • Subclass Labyrinthodontia
      Labyrinthodontia
      Labyrinthodontia is an older term for any member of the extinct subclass of amphibians, which constituted some of the dominant animals of Late Paleozoic and Early Mesozoic times . The group is ancestral to all extant landliving vertebrates, and as such constitutes an evolutionary grade rather...
      
       †
    • Subclass Lepospondyli
      Lepospondyli
      Lepospondyli are a group of small but diverse Carboniferous to early Permian tetrapods. Six different groups are known, the Acherontiscidae, Adelospondyli, Aïstopoda, Lysorophia, Microsauria and Nectridea, and between them they include newt-like, eel- or snake-like, and lizard-like forms, along...
      
       †
    • Subclass Lissamphibia
      Lissamphibia
      The subclass Lissamphibia includes all recent amphibians and means smooth amphibia.Extant amphibians fall into one of three orders — the Anura , the Caudata or Urodela , and the Gymnophiona or Apoda .Although the ancestry of each group is still unclear, all share certain common characteristics,...
      
      
  • Class Reptilia
    • Subclass Anapsida
      • Order Cotylosauria
        Captorhinidae
        Captorhinidae is one of the earliest and most basal reptile families.-Description:...
        
         †
      • Order Chelonia
    • Subclass Synapsida
      • Order Pelycosauria †
      • Order Therapsida
        Therapsida
        Therapsida is a group of the most advanced synapsids, and include the ancestors of mammals. Many of the traits today seen as unique to mammals had their origin within early therapsids, including hair, lactation, and an erect posture. The earliest fossil attributed to Therapsida is believed to be...
        
         †
    • Subclass Euryapsida
      Euryapsida
      Euryapsida is a polyphyletic group of reptiles that are distinguished by a single temporal fenestra, an opening behind the orbit, under which the post-orbital and squamosal bones articulate. They are different from Synapsida, which also have a single opening behind the orbit, by the placement of...
      
      
      • Order Sauropterygia
        Sauropterygia
        Sauropterygia were a group of very successful aquatic reptiles that flourished during the Mesozoic before they became extinct at the end of the era. They were united by a radical adaptation of their shoulder, designed to support powerful flipper strokes...
        
         †
      • Order Ichthyosauria †
    • Subclass Diapsida (lizards & snakes too)
      • Order Crocodilia
        Crocodilia
        Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
        
         (crocodiles, alligators etc.)
      • Order Thecodonts †
      • Order Pterosauria †
      • Order Saurischia
        Saurischia
        Saurischia meaning 'lizard' and ischion meaning 'hip joint') is one of the two orders, or basic divisions, of dinosaurs. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure...
        
         (dinosaurs) †
      • Order Ornithischia
        Ornithischia
        Ornithischia or Predentata is an extinct order of beaked, herbivorous dinosaurs. The name ornithischia is derived from the Greek ornitheos meaning 'of a bird' and ischion meaning 'hip joint'...
        
         (dinosaurs) †
  • Class Aves
    • Subclass Archaeornithes
      Archaeornithes
      The Archaeornithes, classically Archæornithes, is an extinct group of the first primitive, reptile-like like birds. It is an evolutionary grade of transitional fossils, the primitive birds halfway between dinosaur ancestors and the derived modern birds....
      
       (primitive dinosaur-like birds like Archaeopteryx
      Archaeopteryx
      Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
      
      ) †
    • Subclass Neornithes (modern birds and some advanced Cretaceous forms)
      • Superorder Odontognathae
        Odontognathae
        Odontognathae is an extinct superorder of birds found widely in Kansas. The superorder was originally proposed by Alexander Wetmore, who attempted to link fossil birds with the presence of teeth, specifically of the orders Hesperornithiformes and Ichthyornithiformes...
        
         (Cretaceous toothed birds) †
      • Superorder Palaeognathae (ratites)
      • Superorder Neognathae
        Neognathae
        Neognaths are birds within the subclass Neornithes of the class Aves. The Neognathae include virtually all living birds; their sister taxon Palaeognathae contains the tinamous and the flightless ratites....
        
         (All other extant birds)
  • Class Mammalia
    • Subclass Prototheria
      Prototheria
      Prototheria is a taxonomic group, or taxon, to which the order Monotremata belongs. It is conventionally ranked as a subclass within the mammals.Most of the animals in this group are extinct...
      
      
      • Order Monotremata (platypus
        Platypus
        The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young...
        
         and the echidna
        Echidna
        Echidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...
        
        s)
    • Subclass Theria
      Theria
      Theria is a subclass of mammals that give birth to live young without using a shelled egg, including both eutherians and metatherians . The only omitted extant mammal group is the egg-laying monotremes....
      
      
      • Infraclass Metatheria
        Metatheria
        Metatheria is a grouping within the animal class Mammalia. First proposed by Thomas Henry Huxley in 1880, it is nearly synonymous with the earlier taxon Marsupialia though it is slightly wider since it also contains the nearest fossil relatives of marsupial mammals.The earliest known...
        
        
        • Order Marsupialia (kangaroos, dunnarts, opossums, wombats etc.)
      • Infraclass Eutheria
        Eutheria
        Eutheria is a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals than to living marsupials . They are distinguished from noneutherians by various features of the feet, ankles, jaws and teeth...
        
         (placentals)
        • Order Insectivora
          Insectivora
          The order Insectivora is a now-abandoned biological grouping within the class of mammals...
          
          
        • Order Chiroptera (bats)
        • Order Creodonta
          Creodonta
          The creodonts are an extinct order of mammals that lived from the Paleocene to the Miocene epochs. They shared a common ancestor with the Carnivora....
          
          
        • Order Carnivora
          Carnivora
          The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...
          
           (dogs/cats)
        • Order Perissodactyla (horses)
        • Order Artiodactyla (cattle and other ungulates)
        • Order Proboscidea
          Proboscidea
          Proboscidea is a taxonomic order containing one living family, Elephantidae, and several extinct families. This order was first described by J. Illiger in 1881 and encompasses the trunked mammals...
          
           (elephants)
        • Order Edentata
        • Order Cetacea
          Cetacea
          The order Cetacea includes the marine mammals commonly known as whales, dolphins, and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal", was more general. It comes from Ancient Greek , meaning "whale" or "any huge fish or sea...
          
           (whales and dolphins)
        • Order Rodentia (mice, rats etc.)
        • Order Lagomorpha
          Lagomorpha
          The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families, the Leporidae , and the Ochotonidae...
          
           (rabbits)
        • Order Primates (monkeys, apes and primates)