Phytosaurs - family Phytosauridae or Parasuchidae - were a group of large (2 to 12 meters long - average size 3 to 4 meters) semi-aquatic predatory thecodonts that flourished during the Late Triassic period. These long snouted and heavily armoured archosaurs bore a remarkable resemblance to modern crocodiles in size, appearance, and (clearly) life-style, a perfect example of convergence or parallel evolution. Scientific classification - Wikipedia /**/ @import /skins/monobook/IE50Fixes. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Bilateria Acoelomorpha Orthonectida Rhombozoa ?Myxozoa Superphylum Deuterostomia    Chordata (vertebrates, etc. ... Typical Classes Subphylum Urochordata - Tunicates Ascidiacea Thaliacea Larvacea Subphylum Cephalochordata - Lancelets Subphylum Myxini - Hagfishes Subphylum Vertebrata - Vertebrates Petromyzontida - Lampreys Placodermi (extinct) Chondrichthyes - Cartilaginous fishes Acanthodii (extinct) Actinopterygii - Ray-finned fishes Actinistia - Coelacanths Dipnoi - Lungfishes Amphibia - Amphibians Reptilia - Reptiles Aves - Birds Mammalia - Mammals Chordates (phylum Chordata) include the vertebrates, together with... Superclasses Anapsida Eurapsida Diapsida Reptilia was an old kingdom or phylum classification that has since been divided into 4 classes. ... Classes Ichthyosauria Sauropterygia Lepidosauria Archosauria Diapsids (two arches) are a group of tetrapod animals that developed two holes (temporal fenestra) in each side their skulls, about 300 million years ago during the late Carboniferous period. ... Groups Pterosauria Crocodylia (crocodiles) Dinosauria    Aves (birds) Archosaurs (Greek for ruling reptiles) are a group of diapsid reptiles that first appeared during the late Permian (roughly 250 million years ago). ... sub-taxa Family Phytosauridae Family Prestosuchidae Family Ornithosuchidae Family Stagonolepididae Family Rauisuchidae Family Poposauridae Superorder Crocodylomorpha    Sphenosuchia    Order Crocodylia Reference Benton, M. J. 2004, Vertebrate Paleontology Crurotarsi (cross-ankles) is a node-based taxon created by Paul Sereno in 1991 to supplant the old term Pseudosuchia. ... Thecodont (socket-toothed reptile), is a catch-all (paraphyletic) group, now considered an obsolete term, that was formerly used to describe a group of the earliest archosaurs that lived during the Permian and Triassic periods. ... The Triassic is a Geologic period that extends from about 248 to 202 million years (My or megayears) before the present. ... Groups Pterosauria Crocodylia (crocodiles) Dinosauria    Aves (birds) Archosaurs (Greek for ruling reptiles) are a group of diapsid reptiles that first appeared during the late Permian (roughly 250 million years ago). ... Subfamilies Family Crocodylidae    Crocodylinae    Alligatorinae    Gavialinae Crocodylia is an order of large reptiles that scientists believe branched off from class Reptilia about 220 million years ago. ... In evolutionary biology, parallel evolution occurs when two independent species evolve together at the same time in the same ecospace and acquire similar characteristics. ...

Phytosaurs are actually crocodile cousins, as both phytosaurs and proto-crocodiles share a common ancestor among the early Crurotarsi. But familar-looking crocodiles only appear in the late Jurassic period, many millions of years after phytosaurs became extinct at the end of the Triassic. sub-taxa Family Phytosauridae Family Prestosuchidae Family Ornithosuchidae Family Stagonolepididae Family Rauisuchidae Family Poposauridae Superorder Crocodylomorpha    Sphenosuchia    Order Crocodylia Reference Benton, M. J. 2004, Vertebrate Paleontology Crurotarsi (cross-ankles) is a node-based taxon created by Paul Sereno in 1991 to supplant the old term Pseudosuchia. ... The Jurassic period is a major unit of the geologic timescale that extends from about 195 million years BP at the end of the Triassic to 135 million years BP at the beginning of the Cretaceous. ...

These animals were widely distributed, fossils being recovered from Europe, North America, India, Morocco, Thailand, and Madagascar.

Early Discoveries

When the first phytosaur fossils were found, it was not immediately obvious what sort of animal they belonged to. The first phytosaur species known to science was named Phytosaurus cylindricodon - "plant lizard with cylindrical teeth" - by G. Jaeger in 1828 because he mistakenly believed that petrified mud fillings in the jaw were herbivore teeth. The specimen is too poor to be diagnostic, and this species name is no longer valid. The name of the group - Phytosauria - was coined by the German paleontologist Hermann von Meyer in 1861, on the basis of this first species. 1828 was a leap year starting on Tuesday (see link for calendar). ... Christian Erich Hermann von Meyer (September 3, 1801 - April 2, 1869), German palaeontologist, was born at Frankfurt am Main. ... 1861 is a common year starting on Tuesday. ...

The next species to be described Belodon plieningeri von Meyer, in von Meyer and Plieningeri 1844. The altogether more appropriate name Parasuchia ("alongside the crocodiles, as they resembled crocodiles to a great degree) was coined by Thomas Huxley in 1875 along with his discovery and naming of the Indian species Parasuchus hislopi (Chatterjee, 1978), on the basis of a partial snout. The specimen also is usually considreed non-diagnostic, and the name Parasuchus replaced by Paleorhinus. Although the names Parasuchidae and Phytosauridae are variously still used by different specialists, "phytosaur" is the standard generic name for these animals, despite the fact that these animals were clearly shown to be carnivores. 1844 was a leap year starting on Monday (see link for calendar). ... Thomas Huxley Thomas Henry Huxley F.R.S. (May 4, 1825 - June 29, 1895) was a British biologist, known as Darwins Bulldog for his defence of Charles Darwins theory of evolution. ... 1875 was a common year starting on Friday (see link for calendar). ...

Differences from Crocodiles

Despite their great similarities in appearance and lifestyle, there are still a number of minor differences that distinguish phytosaurs from true crocodiles. For one thing, the phytosaur ankle structure is much more primitive than that of any crocodile. Also, phytosaurs lack the bony secondary palate that crocodiles have that enables them to breathe even when the mouth is full of water. It is possible however that phytosaurs had a fleshy palate, as many Mesozoic crocodiles are presumed to have had. Finally, and most noticably, phytosaurs had nostrils placed near or above the level of the eyes, in contrast to crocodiles where the nostrils are near the end of the snout. This adaptation may have developed to allow them to breathe while the rest of the body was submerged. In tetrapods, the tarsi are the cluster of bones in the foot between the tibia and fibula and the metatarsus. ...

Three Morphotypes

The phytosaur skull was characterized by three distinct morphotypes, which relate to feeding and habits and not (as was once thought) evolutionary relationships. These skull patterns are linked to characteristics of the dentition; specifically the differentiation or similarity of the teeth along the jaws.

Dolichorostral ("long snouted") types have a long, slender snout and a large number of conical teeth that are the same throughout. These were most likely piscivorous, able to capture fast slippery prey, but not so good at tackling a land animal. Some examples are Paleorhinus, Rutiodon carolinensis, and Mystriosuchus. At one time it was believed that Paleorhinus and Mystriosuchus belonged to a distinct group of phytosaurs (subfamily of family Mystriosuchinae/Mystriosuchidae Huene, 1915) characterised by this adaptation, but it is now known that Mystriosuchus is actually more closely related to Pseudopalatus, an "altirostral" form (Hungerbühler, 2002).

Brachyrostral ("short snouted") forms are the opposite, they have a massive, broad snout, and very strong skull and jaws; with the front teeth like fangs for holding the prey, and the rear teeth blade-like for slicing the meat into chunks that can easily be swallowed (an animal with different types of teeth like this is called heterodont). These were powerful animals specialised for feeding on strong struggling prey, such as terrestrial animals that come to the water to drink. Examples of this type are Nicrosaurus and Smilosuchus

Altirostral ("high snouted") animals are intermediate between the two, they had heterodont dentition but not as extremely developed as the brachyrostral type. Angistorhinus and Pseudopalatus are typical examples here. These were most likely generalist feeders.

Modern crocodiles exhibit a similar morphological diversity, for example the broad snouted altirostral alligator and the long snouted dolichorostral gavial This article refers to the large reptile. ... Binomial name Gavialis gangeticus (Gmelin, 1789) Taxonomy The Gharial (Gavialis gangeticus) is the only surviving member of the family Gavialidae, a long-established group of crocodile-like reptiles with long, narrow jaws. ...

Phytosaurs were even better protected and armoured than crocodiles, protected by heavy bony scutes (often found as fossils), and the belly reinforced with a dense arrangement of gastralia (abdominal ribs). A scute (Latin scutum, shield) is a horny, chitinous, or bony external plate or scale, as on the shell of a turtle or the underside of a snake. ...

Evolutionary Histroy and Relationships

Phytosaurs first appear during the Carnian age, evolving from an unspecified crurotarsan ancestor. There are no clear intermediate forms, as the first phytosaurs were already fully-formed and highly specialised.

The earliest phytosaurs belong to the primitive and unspecialised but very widely distributed genus Paleorhinus. A somewhat more advanced and larger form, Angistorhinus appears at the same time or soon after. Later in the Carnian both these animals are replaced by more specialised forms like Rutiodon, Leptosuchus, and the huge Smilosuchus (Lucas 1998). The Carnian-Norian extinction means that these animals die off, and the Early Norian sees new genera like Nicrosaurus and Pseudopalatus, both of which belong to the most derived clade of phytosaurs, the Pseudopalatinae. Later in the middle Norian the advanced and specialised fish-eater Mystriosuchus appears. Fossil remains of this widespread animal is known from Germany, northern Italy, and Thailand. Finally the large Redondasaurus in south-west North America and the long-snouted (altirostral) Angistorhinopsis ruetimeyeri in Europe continue the group into the Rhaetian. Phytosaur footprints (the ichnotaxon Apatopus) are also known from the latest Rhaetian of the East Coast of USA (the Newark Supergroup) (Olsen et al. 2002). This indicates that phytosaurs continued as successful animals until the very end of the Triassic, when, along with other large crurotarsan archosaurs, they were killed off by the end Triassic extinction event. It was to be some fifty million years or so before any similar reptiles would appear (early true crocodiles were either small and fully terrestrial or completely marine. The Triassic-Jurassic extinction event is one of the major extinction events of the Phanerozoic eon, profoundly affecting life on land and in the oceans. ... Orders  Crocodylia - Crocodilians  Rhynchocephalia - Tuataras  Squamata   Suborder Sauria - Lizards   Suborder Serpentes - Snakes Testudines - Turtles Superorder Dinosauria  Saurischia  Ornithischia The reptiles are a group of vertebrate animals. ...

External links

• Translation and Pronunciation Guide (http://www.dinosauria.com/dml/names/phytoi.htm)

• A Preliminary Biomechanical Analysis of Phytosaur Life Habits (http://www.faculty.de.gcsu.edu/~bwall1/Publications/Phytosaur.htm)

• Phytosauria - Palaeos (http://www.palaeos.com/Vertebrates/Units/270Archosauromorpha/270.530.html)

• Mikko's Phylogeny (http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Archosauria/Pseudosuchia/Phytosauria.htm) - cladistic tree

• Great Triassic Assemblages Pt 1 - The Chinle and Newark (http://rainbow.ldeo.columbia.edu/courses/v1001/chinlenewark10.html) - some material on phytosaurs

References

• Carroll, RL (1988), Vertebrate Paleontology and Evolution, WH Freeman & Co.

• Chatterjee, S (1978), A primitive parasuchid (phytosaur) reptile from the Upper Triassic Maleri Formation of India, Palaeontology 21: 83-127

• Hungerbühler A. (2002), The Late Triassic Phytosaur Mystriosuchus Westphali, With A Revision of the Genus. Palaeontology, March 2002, vol. 45, no. 2, pp. 377-418(42)

• Lucas, SG (1998), Global Triassic tetrapod biostratigraphy and biochronology. Paleogeog. Palaeoclimatol., Palaeoecol. 143: 347-384.

• Olsen, P.E., Kent, D.V., H.-D.Sues,, Koeberl, C., Huber, H., Montanari, E.C.Rainforth, A., Fowell, S.J., Szajna, M.J., and Hartline, B.W., (2002) Ascent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundary. Science, vol. 296, p. 1305-1307.