Palæos: Paleozoic		Guadalupian Epoch
PERMIAN PERIOD		Wordian Age

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Tetrapods

The Dinocephalian Terrestrial empire

The Wordian saw the continuation of the earlier Roadian age fauna, but with several changes. The is supplanted (and for the most part replaced) by a rich range of early therapsids. It is not unlikely that these early therapsids may have had the beginnings of metabolic development towards the mammalian condition, but I cannot agree with Dr Bakker that they were already partially or fully endothermic. In any case, these animals quickly radiated into an extraordinary variety of large and small terrestrial herbivores and carnivores. The Early Permian ectothermic families died out early during, or perhaps prior to, this time.

During this time, all the big herbivores and carnivores were great lumbering creatures; some of which may have been semi-aquatic, while others were fully terrestrial. Most were of the Dinocephalian type. These were impressive-looking beasts easily recognized by their distinctive dentition of intermeshing incisors. The largest were the size of a modern rhinoceros. Dinocephalian faunas of Wordian age have been found in Russia, South Africa, and China, and it is assumed these animals had a Pangea-wide distribution.

Although the Wordian age was ruled by large and small primitive therapsids, these were also accompanied by a rich fauna of stem tetrapods and unspecialized reptiles.

The tetrapods were mostly large semi-aquatic fish-eaters, superficially crocodile-like in appearance, although there were also a selection of smaller aquatic and fully terrestrial types. Apart from the aquatic batrachosaurs, all belong to the Temnospondyli

As regards the reptiles, these included two main types. The Anapsida were a successful group of mostly small and lizard-like Permo - Triassic reptiles. At one time they were thought to be the most primitive of the reptiles, but they actually only appear after the other, more "advanced" forms like the diapsids and synapsids. One lineage of anapsids evolved into big plant-eaters (the Pareiasauria). It is still not known whether turtles are related to these reptiles

The other group, the pelycosaurs, were primitive (unspecialized) synapsids that had dominated the early Permian. But now they were on their way out, as their new, more capable, and more metabolically active descendents, the therapsids, were taking over. Even so, several lineages of pelycosaurs continued to fill the role of small to large tropical lizards. These included both herbivorous and specialized forms like the Caseidae, and insectivorous forms like the Varanopseidae. Both were small, especially relative to the giants of the preceding Roadian epoch. The caseids died out before the end of the Wordian, but the varanopsids continued into the following Capitanian age.

Whilst non-therapsid reptiles experienced little change over this period, the same cannot be said for the Therapsids. Those from the Wordian are quite distinct from those of the preceding Roadian age. The reason for such rapid evolution is not clear. Bob Bakker suggests it is tied in to the active mammalian metabolism he suggests these synapsids (or proto-mammals) developed. But even mammals and other active animals like dinosaurs can persist with little change for some millions of years. So either the dating is wrong (allowing an insufficient period of time, and the beginning of the Roadian extends back several million years earlier), there were stressful factors in the environment (for example, the Permo-Carboniferous ice age) that accelerated the rate of evolution, or the therapsid faunas represented here actually began in the Kungurian (however, all references agree in locating the Ocher fauna during the Kazanian (=Roadian)).

Stratigraphy of Tetrapods from East Europe

The following stratigraphic table, based mostly on information in Olson, 1962, King, 1990 and Hancox and Rubidge, 1997, catalogues the occurrence of Wordian tetrapods in East Europe and South Africa. (Chinese Dinocephalian fauna not shown)

Early Wordian (early "Zone II")

Age of the Deuterosaurs and Brithopines

Order: Procolophonia Superfamily Procolophonoidea Family Nyctiphruretidae Nyctiphruretus acudens Efremov, 1938 Horizon: Belebei-Mezen Cotylosaur Complex Locality: Mezen River, Arkhangelsk Region, northern European Russia Length (skull): 4.4 cm Length (total): 36 cm Comments: a small herbivorous reptile, preserved in lake sediments. The name means "Guardian of the Night" Links: Nyctiphruretus page

Order Pelycosauria Suborder Caseasauria Family Caseidae Ennatosaurus tecton Efremov, 1956 Horizon: / Locality: Pinega River, Arkhangelsk Region, northern European Russia Specimens: large numbers of individuals found in a single sandstone layer Size: about the size of a domestic cat Comments: The last and most specialized of the Caseids. The skull is similar to but more derived than that of Cotylorhynchus. The body however is tiny in comparison. It was originally thought that these were juvenile bodies associated with adult skulls. The name means "Ninth Reptile" Links: Ennatosaurus page

Order Pelycosauria Suborder Eupelycosauria Family Varanopseidae Mesenosaurus romeri Efremov, 1938 Horizon: Belebei-Mezen Cotylosaur Complex Locality: Mezen River, Arkhangelsk Region, northern European Russia Length (total): 38 cm Size: Size of a medium-sized lizard Diet: invertebrates Links: Mesenosaurus page

Therapsids - The Bashkirian Fauna

Suborder "Biarmosuchia" (basal Therapsids)
Family Phthinosuchidae

 

Phthinosuchus discors

Horizon: Early Tatarian
Locality: Uralian Cupric Sandstones, Bashkiry, Western Cisuraly, Russia
Specimens: fragmentary skull
Length: about 2 meters?
Comments: This is one of those animals that has been widely drawn and reconstructed, but which is known from such poor material that little can really be said about it. It appears to be related to Bairmosuchus
References: Sigogneau-Russell 1989

sketch (above and left) © 2001 by Vince R Ward - Prehistoric Pages

Suborder Dinocephalia
Plesion Anteosauria
Family Brithopodidae
Subfamily Deuterosaurinae (monogeneric)

Deuterosaurus biarmicus Eichwald 1860

Horizon: Copper Sandstones, Upper Kazanian/Lower Tatarian substage (Bashkirian Subzone)
Locality: Orenburg Province, Russia
Length (skull): 23 cm
Length (total): about 1.5 meters?
Diet: herbivorous (or partially omnivorous)
Comments: A lineage of distinctive-looking short-headed herbivorous brithopodids. They seem to have died out before the end of the Wordian age. Olson 1962 incorrectly separates Deuterosaurus from the rest of the Brithopodids. Boonstra 1969, and following him King 1988, includes the genus under the Anteosauridae/inae/ini. It is perhaps better simply to see the Deuterosaurs as a separate short-lived experiment in dinocephalian herbivory. The name means "Second Lizard"
References: King 1988

The Kargalian Fauna

After about a million years or so, the Bashkirian animals have grown larger. Admetophoneus, "Deuterosaurus" gigas, and Brithopus ponderus all appear. These were probably semi-aquatic forms. There is no trace of the caseids, which may have died out.

The Eodicynodon fauna

Away from the tropical swamps of northern Pangea, a different fauna has evolved in the cooler southern latitudes. This is characterized by a variety of advanced anomodonts. Two forms are shown below:

sketch © 2001 by Vince R Ward - Prehistoric Pages Suborder Dinocephalia Family Tapinocephalidae Tapinocaninus pamelae Rubidge 1991 Horizon: Eodicynodon Zone, Lower Beaufort Beds Locality: Karroo, South Africa Length: about 3 meters Weight: 1000 kg Comments: earliest known Tapinocephalid Reference: Rubidge, 1991

sketch © 2001 by Vince R Ward - Prehistoric Pages Suborder Anomodontia Infraorder Dicynodontia Family Eodicynodontidae Eodicynodon Horizon: Eodicynodon Zone, Lower Beaufort Beds Locality: Karroo, South Africa Length (skull): 9 cm Length (total): 30 cm Comments: the earliest known dicynodont

The Isheevo Megafauna

Occurring at the very end of the Wordian or the beginning of the Capitanian are a number of well-known very large dinocephalians, such as Titanophoneus, Doliosauriscus (probably cogeneric with Anteosaurus), and Ulemosaurus. These represent a considerable advance over the Kargalian Megafauna, indicating that some period of time has passed. The dating is controversial, either Late Wordian or Earliest Capitanian. Also continuing at this time are the stem tetrapods Platyoposaurus and Melosaurus.