TAXA OF LIFE


Animal Kingdom

HIERARCHICAL CLASSIFICATION OF THE CLASS ANAPSIDA

EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>BILATERIA>DEUTEROSTOMATA>CRANIATA>TETRAPODA>AMNIOTA>ANAPSIDA

The attached descriptions come from Benton (2005) and the Animal Diversity Web from the University of Michigan Museum of Zoology.  The structure of the system is also based, in part, on the phylogenetic treatment by Mikko's Phylogeny Web (from the Finnish Museum of Natural History).     Taxa in red are extinct.  

 

CLASS ANAPSIDA

The anapsids, as the name implies, have no temporal fenestrae.  Furthermore, they have (had) no caniniform maxillary teeth, and the shaft of the femur is (was) long and slender ( Benton, 2005).  In this system, the anapsids have two orders.  The Basal Anapsid Families are placed into an unnamed order that almost certainly is paraphyletic.  They include animals that were fully aquatic carnivores to large, terrestrial herbivores.  The second order, Testudines, is monophyletic and includes the turtles and their relatives. The anapsids are a sister group to the diapsids, and the synapsids are the outgroup.

 

ORDER PARAREPTILIA (BASAL ANAPSID FAMILIES)+

FAMILY MESOSAURIDAE

These animals were aquatic and relatively small (1m and smaller).  They had a relatively long neck and a long, flattened tail.  The long, narrow jaws are lined with needle-like teeth that interlock as the jaws close.  They may have used them to trap small fish or to strain out aquatic invertebrates.

Lower Permian

Mesosaurus

FAMILY MILLERETTIDAE

Insectivores. The skulls of these animals resembled lizards.  They have a temporal fenestra, but the bar is incomplete.  

Upper Permian

Millerosaurus

FAMILY BOLOSAURIDAE

The animals in this group had achieved bipedal locomotion.  Hind legs were longer than the front legs.  Also, its feet were long, and it must have run on its toes.  Bulbous occluding teeth (likely a herbivore that specialized on tough plants).

FAMILY PROCOLOPHONIDAE

These animals had horn-like projections on the sides of the skull (defensive?).  Cheek teeth blunt and occluding.  Also, herbivores of tough plants.  Broad feet suggest that they were burrowers. 

Upper Permian to Upper Triassic

Procolophon

FAMILY PAREIASAURIDAE

These were relatively large stocky herbivores.  They had a bony frill extending from the sides of the skull and projections from the lower jaw.  Legs and feet were elephant-like.  They had a very muscular neck.  This has been suggested as the sister-group to the turtles.

Upper Permian

Pareiasaurus, Elginia, Scutosaurus.

ORDER TESTUDINES (CHELONIA) The Turtles

These are anapsids that are toothless with a horny beak.  The body is flattened and a shell formed by modified ribs (above) and a bony plastron below.  The bone is overlain by overlapping plates of keratin.

FAMILY PROGANOCHELIDAE

Characters typical of turtles except it has a palate with teeth and a large embayment in the skull for the eardrum. The palate is loosely connected to the braincase. 

Upper Triassic

Proganochelys, Proterocheris

FAMILY ASTRALOCHELIDAE

The palate is fused to the braincase and the eardrum is partially encased in bone.

Lower Jurassic

Astralochelys

  CASICHELYDIA: Turtles that can retract their heads into the carapace (some extinct forms could not do this). 

  SUBORDER PLEURODIRA

These turtles retract their heads sideways. The jaw muscles pass over the trochlea, a knob formed by the ptergoid.

Upper Triassic to present

Proterochersis+,

FAMILY CHELIDAE

Austro-American Side-Necked Turtles (also called Snake-Necked Turtles).  Generally animals of slow-moving streams and swamps of  Australia, New Guinea, and South America.  The neck is very long and retracts by an s-shaped lateral motion thus causing distinctive structural changes in the neck.  They are carnivores with a broad range of aquatic prey.

Miocene to present.

Acanthochelys, Chelodina, Chelus, Elseya, Elusor, Emydura, Hydromedusa, Phrynops, Platemys, Pseudemydura, Rheodytes.

FAMILY PELOMEDUSIDAE

Afro-American Side-Necked Turtles.  These are animals of swamps, rivers, ponds, and temporary waters of Africa , Madagascar , and South America .  Pelomedusids have no cervical scute, and distinctive nasal bone, splenial bone, and cervical vertebrae.  These can be omnivores. 

Erymnochelys, Pelomedusa, Peltocephalus, Pelusios, Podocnemis, Stupendemys+.

  SUBORDER CRYPTODIRA

These turtles retract their heads straight back by making a vertical bend in the neck. The trochlea is formed the otic capsule, further back that in the pleurodires.

Lower Jurassic to present

SUPERFAMILY UNNAMED

The basal cryptodires are characterized by retaining ptergoid teeth.

Lower Jurassic

Kayentachelys

SUPERFAMILY BAENOIDEA+

Characteristic narrow snout.

Upper Jurrasic to Eocene

FAMILY BAENIDAE

Baena, Polythorax, Probaena, Trinitichelys, Hayemys, Eubaena, Plesiobaena, Palatobaena, Dorsetochelys, Uluops.

FAMILY CHENGYUCHELYIDAE

Chengyuchelys, Sichuanchelys.

FAMILY NEURANKYLIDAE

Boremys, Compsemys, Naomechelys, Neurankylus, Thescelus.

SUPERFAMILY UNNAMED

FAMILY MEIOLANIIDAE Modesto 1999).  Mesosaurids were used by Wegener (1915

These had broad skulls (up to 50 cm wide) with horns.

Pleistocene

Crossochelys, Niolamia, Ninjemys, Warkalania, Meiolania.

    SUPERFAMILY CHELONIOIDEA

Sea turtles.  These marine turtles show an elongation of digits 3 and 4; the carpals and tarsals are flattened; and share a particular articulation between the 8th cervical vertebra and the nuchal bone.  The limbs are flippers; the forelimbs are larger than the hind limbs. 

FAMILY PLESIOCHELYIDAE+

Craspedochelys, Hylaeochelys, Neusticemys, Plesiochelys, Portlandemys, Tienfuchelys, Desmemys.

FAMILY CHELONIIDAE

Sea Turtles.  Marine animals of all tropical seas.  These animals are large; the carapace can be up to 2.1m long.  The unifying synapomorphy is a platycoelous articulation between the 6th and 7th cervical vertebrae.  They nest on particular sandy beaches.  Omnivores.

Upper Cretaceous to present

Caretta, Chelonia, Eretmochelys, Lepidochelys, Natator.

FAMILY DERMOCHELYIDAE

Leatherback Turtles.  Marine with distributions from the tropical seas toward the poles.  This is the largest of all the extant turtles (a carapace almost 2.5m long).  The carapace is leathery with embedded osteoderms; and it has 7 elongate ridges (keels).  These feed almost entirely on jellyfish.  The head cannot be retracted and the 4th cervical vertebra is biconvex.  They nest on sandy beaches.

Dermochelys.

    SUPERFAMILY TRINYCHOIDEA

Softshell Turtles

FAMILY TRIONYCHIDAE

Softshell Turtles.  Freshwater (rarely brackish water) of eastern North America , Africa , Asia, and Australia .  Softshells are very flattened and heads have elongate rostra.  Most of the carapace skeleton is lost.  They have the following synapomorphies: fleshy lips over the keratin beak, no articulation between the centra of the last cervical and first thoracic vertebrae, and claws only on the middle three digits.  Mainly carnivores.

Late Jurassic to the present

Amyda, Apalone, Aspiderestes, Chitra, Cyclanorbis, Cycloderma, Dogania, Lissemys, Nilssonia, Palea, Pelochlys, Pelodiscus, Rafetus, Trionyx.

FAMILY CARETTOCHELYIDAE

Pignose Turtles.  Freshwater (and brackish water) of rivers and lagoons in New Guinea and Australia .  The carapace is leathery; and they have an elongate, pig-like snout.  Synapomorphies include: paired articulation between 8th vertebra and the nuchal bone, limbs terminate in paddles.

Eocene to the present

Carettochelys.

FAMILY DERMATEMYDIDAE

Mesoamerican River Turtles.  Large rivers and lakes of Central America .  It is almost completely aquatic and performs a significant amount of gas exchange between the lining of the nasal passage and water. 

They have an extensive fossil history Cretaceous to the Miocene and represented today by a single species.

Dermatemys.

FAMILY KINOSTERNIDAE

Mud Turtles and Musk Turtles.  Freshwater (slow streams and lakes) of the Americas .  The carapace may have a keel.  The plastron is cross-shaped and may be hinged.  Synapomorphies include: 10 pairs of peripheral bones, an acetabulum with an illio-ischial notch, frontal bone does not touch the orbit.  All are carnivores. 

Oligocene to present

Claudius, Kinosternon, Staurotypus, Sternotherus.

SUPERFAMILY TESTUDINOIDEA

Tortoises

FAMILY TESTUDINIDAE

Tortoises.  Terrestrial in warm climates (deserts to rainforests) of the Americas , Eurasia , Africa , Madagascar , the Galapagos, and the Aldabra atoll.  The carapace has a high dome and the plastron is almost complete and usually lacks a hinge.  They have pillar-like legs and have 4 digits on the hind legs.  Mainly herbivores.  Good fossil history.

Lower Eocene to present

Agrionemys, Dipsochelys, Furculachelys, Geochelone, Gopherus, Homopus, Indotestudo, Kinixys, Malocochersus, Manouria, Platysternon, Psammobates, Pyxis, Testudo.

FAMILY EMYDIDAE

Box Turtles and Pond Turtles.  Freshwater and brackish water species of North America , northern South America , Europe , northwestern Africa , and Asia .  Structural synapomorphies are very few: no contact between the squamosal and parietal bones; and the frontal bone forms part of the orbit.  They range from carnivory to herbivory.

Upper Cretaceous to the present

Batagur, Callagur, Chinemys, Chrysemys, Clemmys, Cuora, Cyclemys, Deirochelys, Emydoidea, Emys, Geoclemys, Geomyda, Graptemys, Hardella, Heosemys, Hieremys, Kachuga, Malaclemys, Malayemys, Mauremys, Melanochelys, Morenia, Notochelys, Ocadia, Orlitia, Pseudemys, Pyxidea, Rhinoclemmys, Sacalia, Siebenrockiella, Terrapene, Trachemys, Gyremys+.

INCERTAE SEDIS

FAMILY CAPTORHINIDAE

Relatively small animals with a skull that was much broader at the back.  The dentition was heterodont.  The cheek teeth grew in multiple parallel rows (parallel to the axis of the dentary).  The multiple teeth suggest that they were herbivores specializing in very tough plants or hard-shelled invertebrates.  These animals, although anapsid, likely were in the line leading to the diapsids (Eodiapsida + Leptosauromorpha + Archaesauromorpha).

Permian

Captorhinus

FAMILY PROTOROTHYRINIDAE+

This is family likely was the basal anapsids.  Lizard-like insectivores.  Their position is unclear; they may be basal to the synapsids, diapsids, and anapsids.

Upper Carboniferous (Pennsylvanian) to lower Permian.

Hylonomus, Paleothrys.

 

LITERATURE CITED

Benton, M. J. 2005. Vertebrate Paleontology. Third Edition. Blackwell Publishing, Malden, MA. 

Hill. R. V. 2005. Integration of morphological data sets for phylogenetic analysis of Amniota: The importance of integumentary characters and increased taxonomic sampling.  Systematic Biology. 54: 530-547.

Modesto, S. P. 1999. Observations on the structure of the eraly Permian reptile Stereosternum tumidum Cope. Paleontologia Africana. 35: 7-19.

Pough, F. H., R. M. Andrews, J. E. Cadle, M. L. Crump, A. H. Savitzsky, and K. D. Wells. 1998. Herpetology. Prentice Hall. Upper Saddle River, NJ. 

Pough, F. H., C. M. Janis, and J. B. Heiser. 2009. Vertebrate Life. 8th ed. Benjamin Cummings. New York. pp. 688. 

Rieppel, O. 2000. Turtles as diapsid reptiles.  Zoologica Scripta. 29: 199-212.

Wegener, A. 1915 (reprinted 1929 and 1966).  Die Entstehung der Kontinente und Ozeane [The Origin of Continents and Oceans]. Friedr. Vieweg and Sohn. Braunschweig.  Translated and reprinted by Dover Publications, Inc. New York.

 

By Jack R. Holt.  Last revised: 12/24/2009