Pristerognathus Assemblage Zone

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Pristerognathus Assemblage Zone
Stratigraphic range: Middle Permian
Alopecognathus angusticeps DB.jpg
Glanosuchus macrops (formerly " Pristerognathus vanderbyli ")
Type Biozone
Unit ofUpper Abrahamskraal Formation and Teekloof Formation of the Beaufort Group
Underlies Tropidostoma Assemblage Zone
Overlies Tapinocephalus Assemblage Zone
Thicknessup to 984.252 feet (300 m)
Location
Region Northern, Western & Eastern Cape
CountryFlag of South Africa.svg  South Africa
Extent Karoo Basin
Type section
Named for Pristerognathus polyodon
Named byKeyser & Smith
Year defined1979

The Pristerognathus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Abrahamskraal Formation and lowermost Teekloof Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching not more than 300 metres (980 ft), occur just east of Sutherland through to Beaufort West in the south and Victoria West in the north. Exposures are also found west of Colesberg and south of Graaff-Reinet. The Pristerognathus Assemblage Zone is the third biozone of the Beaufort Group. [1] [2] [3]

Contents

The name of the biozone refers to Pristerognathus polyodon , a medium-sized carnivorous therocephalian therapsid. It is characterized by the presence of this therocephalian species in association with Diictodon feliceps , a small, fossorial dicynodont whose fossils are especially common in this biozone.

History

The first fossils to be found in the Beaufort Group rocks that encompass the current eight biozones were discovered by Andrew Geddes Bain in 1856. [4] However, it was not until 1892 that it was observed that the geological strata of the Beaufort Group could be differentiated based on their fossil taxa. The initial undertaking was done by Harry Govier Seeley who subdivided the Beaufort Group into three biozones, [5] which he named (from oldest to youngest):

These proposed biozones Seeley named were subdivided further by Robert Broom between 1906 and 1909. [6] Broom proposed the following biozones (from oldest to youngest):

The Pristerognathus Assemblage Zone as it currently stands was defined by Keyser and Smith in the late 1970s. Initially the biozone included the upper 300m of the underlying Tapinocephalus Assemblage Zone due to the disappearance of Dinocephalian fossils in those rock deposits and had been named the Pristerognathus-Diictodon Assemblage Zone. After further research on the rocks of the middle Permian, it was understood that the disappearance of the dinocephalians was not an indication of the boundary of the Tapinocephalus Assemblage Zone, and the extra 300m of rock was subsequently restored to the underlying Tapinocephalus Assemblage Zone.

Lithology

The Pristerognathus Assemblage Zone correlates with the upper Abrahamskraal Formation, the lowermost Teekloof Formation west of 24°E and to the Middleton Formation east of 24°E, Adelaide Subgroup of the Beaufort Group. This biozone is considered to be Middle Permian (Guadalupian) in age. [7]

The rocks of the Pristerognathus Assemblage Zone are similar to the underlying Tapinocephalus Assemblage Zone although is dominated by multistory sandstone deposits. The sandstones are interspaced with silt-rich greenish-grey mudstones and subordinate reddish-brown mudstone layers. [8] Calcareous nodules, which weather out brown, are often found in the mudstone layers. Pinkish chert bands are found in the lowermost mudstone deposits of this biozone. The Pristerognathus Assemblage Zone is also known for containing uranium deposits. [1] The presence of the chert band confirms that there was volcanic activity taking place during the time the rock sediments were deposited. The rocks of the lower Pristerognathus Assemblage Zone were deposited at the end of the middle Permian (end-Guadalupian) extinction event, which is currently thought to have been caused by the eruption of the Emeishan Large Igneous Province. [9] [8]

The depositional environment of the Pristerognathus Assemblage Zone was likewise similar to the Tapinocephalus Assemblage Zone, having been formed by sedimentary material being deposited by vast, fluvial plains. These fluvial plains flowed northwards from a foreland basin that was being formed from the rising of the Gondwanide mountains in the south. The Gondwanides were the result of crustal uplift that had previously begun to take course due to tectonic activity. The pressure of the growing Gondwanides mountain chain caused the formation of the Karoo Basin where the deposits of the Pristerognathus Assemblage zone, and all other succeeding assemblage zone deposits, were deposited over tens of millions of years. [10] [2]

Paleontology

Vertebrate fossils are most commonly found in the mudstone deposits of the Pristerognathus Assemblage Zone, especially within the calcareous nodules. [11] This biozone is characterized by the presence of Pristerognathus polyodon and its other subspecies Pristerognathus baini and Pristerognathus vanderbyli. Pristerognathus fossils are usually found associated with those of Diictodon . The fossils of both these taxa are the most commonly found; other fossil taxa are markedly more rare. Species diversity dropped off after the end-Guadalupian extinction, which is the reason that this biozone is lacking in species richness. Other taxa that have been found in this biozone include a couple pareiasaur species, namely Bradysaurus , the putative pantestudine Eunotosaurus africanus , [12] [13] and the varanopid pelycosaur Heleosaurus scholtzi . [14] [15] [16] Fossils of the biarmosuchian Hipposaurus boonstrai [17] are likewise found including some gorgonopsid species. [18] Other dicynodont species found include Endothiodon uniseries and Pristerodon mackayi . Finally, fossils of temnospondyl amphibians such as of Rhinesuchus whaitsi , [19] the fishes Namaichthys and Atherstonia, invertebrate trackways, burrows, and feeding trails such as of Planolites and a variety of plant fossils, namely of Glossopteris , Phyllotheca , and Schizoneura, have been recovered. [1] [20] Some fossil taxa that have been found from this biozone, namely Hipposaurus , have been recovered from geological formations from different countries which correlate in age. Hipposaurus fossils have been found in the Madumabisa Mudstone Formation in Zambia. [17] [21]

See also

Related Research Articles

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<i>Diictodon</i> Extinct genus of dicynodonts

Diictodon is an extinct genus of pylaecephalid dicynodont. These mammal-like synapsids lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in the Cistecephalus Assemblage Zone of the Madumabisa Mudstone of the Luangwa Basin in Zambia and the Tropidostoma Assemblage Zone of the Teekloof Formation, Tapinocephalus Assemblage Zone of the Abrahamskraal Formation, Dicynodon Assemblage Zone of the Balfour Formation, Cistecephalus Assemblage Zone of the Middleton or Balfour Formation of South Africa and the Guodikeng Formation of China. Roughly half of all Permian vertebrate specimens found in South Africa are those of Diictodon. This small herbivorous animal was one of the most successful synapsids in the Permian period.

<span class="mw-page-title-main">Beaufort Group</span> Third of the main subdivisions of the Karoo Supergroup in South Africa

The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underlies the Stormberg Group. Based on stratigraphic position, lithostratigraphic and biostratigraphic correlations, palynological analyses, and other means of geological dating, the Beaufort Group rocks are considered to range between Middle Permian (Wordian) to Early Triassic (Anisian) in age.

<i>Tapinocephalus</i> Assemblage Zone

The Tapinocephalus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the middle Abrahamskraal Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 2,000 metres (6,600 ft), occur from Merweville and Leeu-Gamka in its southernmost exposures, from Sutherland through to Beaufort West where outcrops start to only be found in the south-east, north of Oudshoorn and Willowmore, reaching up to areas south of Graaff-Reinet. Its northernmost exposures occur around the towns Fraserburg and Victoria West. The Tapinocephalus Assemblage Zone is the second biozone of the Beaufort Group.

<i>Cistecephalus</i> Assemblage Zone

The Cistecephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the Teekloof Formation north-west of Beaufort West in the Western Cape, in the upper Middleton and lower Balfour Formations respectively from Colesberg of the Northern Cape to east of Graaff-Reinet in the Eastern Cape. The Cistecephalus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Late Permian in age.

<i>Daptocephalus</i> Assemblage Zone

The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.

<i>Lystrosaurus</i> Assemblage Zone

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<i>Cynognathus</i> Assemblage Zone Biozone which correlates to the Burgersdorp Formation of the Beaufort Group

The Cynognathus Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossiliferous and geologically important Karoo Supergroup. The Cynognathus Assemblage Zone is the youngest of the eight biozones found in the Beaufort Group, and is considered to be late Early Triassic (Olenekian) to early Middle Triassic (Anisian) in age. The name of the biozone refers to Cynognathus crateronotus, a large and carnivorous cynodont therapsid which occurs throughout the entire biozone.

<i>Tropidostoma</i> Assemblage Zone

The Tropidostoma Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the lower Teekloof Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 240 metres (790 ft), occur from east of Sutherland through to Beaufort West and Victoria West, to areas south of Graaff-Reinet. Its northernmost exposures occur west/north-west of Colesberg. The Tropidostoma Assemblage Zone is the fourth biozone of the Beaufort Group.

<i>Eodicynodon</i> Assemblage Zone

The Eodicynodon Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the Abrahamskraal Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 620 metres (2,030 ft), occur south-east of Sutherland, north of Prince Albert, and south-east of Beaufort West. The Eodicynodon Assemblage Zone is the lowermost biozone of the Beaufort Group.

<i>Tapinocaninus</i> Extinct genus of therapsids

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Elliotsmithia is a small varanopid synapsid found from the late Middle Permian of South Africa. It is the sole basal synapsid "pelycosaur" known from the supercontinent Gondwana and only two specimens have been yielded to date. Its species name longiceps is derived from Latin, meaning "long head". Both known Elliotsmithia fossils were recovered from Abrahamskraal Formation rocks—within the boundaries of the Tapinocephalus Assemblage Zone—of the lower Beaufort Group. It was named for the late Sir Grafton Elliot Smith in 1937.

<i>Tropidostoma</i> Extinct genus of dicynodonts

Tropidostoma is a medium-sized herbivorous oudenodontid dicynodont therapsid that lived during the Late Permian (Lopingian) period in South Africa. The first Tropidostoma fossil was described by Harry Govier Seeley in 1889. Later two subspecies were identified. Tropidostoma fossils are an index fossil in a biozone of the Karoo Basin known as the Tropidostoma Assemblage Zone. This biozone is characterized by the presence of this species in association with another dicynodont species, Endothiodon uniseries.

<i>Criocephalosaurus</i> Extinct genus of therapsids

Criocephalosaurus is an extinct genus of tapinocephalian therapsids that lived in Southern Africa during the Guadalupian epoch of the Permian. They are the latest surviving dinocephalians, extending past the Abrahamskraal Formation into the lowermost Poortjie Member of the Teekloof Formation in South Africa. They are also regarded as the most derived of the dinocephalians, alongside Tapinocephalus, and the most abundant in the fossil record.

<span class="mw-page-title-main">Abrahamskraal Formation</span> Geological formation of the Beaufort Group in South Africa

The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.

<span class="mw-page-title-main">Balfour Formation</span> Geological formation in the Beaufort Group of South Africa

The Balfour Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Balfour Formation is the uppermost formation of the Adelaide Subgroup which contains all the Late Permian-aged biozones of the Beaufort Group. Outcrops and exposures of the Balfour Formation are found from east of 24 degrees in the highest mountainous escarpments between Beaufort West and Fraserburg, but most notably in the Winterberg and Sneeuberg mountain ranges near Cradock, the Baviaanskloof river valley, Graaff-Reniet and Nieu Bethesda in the Eastern Cape, and in the southern Free State province.

<span class="mw-page-title-main">Katberg Formation</span> Geological formation in the Beaufort Group of the Karoo Supergroup in South Africa

The Katberg Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Katberg Formation is the lowermost geological formation of the Tarkastad Subgroup which contains the Lower to Middle Triassic-aged rocks of the Beaufort Group. Outcrops and exposures of the Katberg Formation are found east of 24 degrees on wards and north of Graaff-Reniet, Nieu Bethesda, Cradock, Fort Beaufort, Queensdown, and East London in the south, and ranges as far north as Harrismith in deposits that form a ring around the Drakensberg mountain ranges.

<span class="mw-page-title-main">Middleton Formation</span> Late middle Permian geological formation in the Eastern Cape

The Middleton Formation is a geological formation that extends through the Northern Cape, Western Cape, and Eastern Cape provinces of South Africa. It overlies the lower Abrahamskraal Formation, and is the eastern correlate, East of 24ºE, of the Teekloof Formation. Outcrops and exposures of the Middleton Formation range from Graaff-Reinet in the Eastern Cape onwards. The Middleton Formation's type locality lies near the small hamlet, Middleton, approximately 25 km south of Cookhouse. Other exposures lie in hillsides along the Great Fish River in the Eastern Cape. The Middleton Formation forms part of the Adelaide Subgroup of the Beaufort Group, which itself forms part of the Karoo Supergroup.

<span class="mw-page-title-main">Teekloof Formation</span> Late Permian geological formation that forms part of the Beaufort Group of South Africa

The Teekloof Formation is a geological formation that forms part of the Beaufort Group, one of the five geological groups that comprises the Karoo Supergroup in South Africa. The Teekloof Formation is the uppermost formation of Adelaide Subgroup deposits West of 24ºE and contains Middle to Late Permian-aged deposits and four biozones of the Beaufort Group. It overlies the Abrahamskraal Formation. The Teekloof Formation does not underlie other units other than the younger Karoo dolerites and sills that relate to the emplacement of the Early Jurassic Drakensberg Group to the east. Outcrops and exposures of the Teekloof Formation range from Sutherland through the mountain escarpments between Fraserburg and Beaufort West. The northernmost localities of the Teekloof Formation are found by Loxton, Victoria West and Richmond.

Phorcys is an extinct genus of gorgonopsian that lived during the Middle Permian period (Guadalupian) of what is now South Africa. It is known from two specimens, both portions from the back of the skull, that were described and named in 2022 as a new genus and species P. dubei by Christian Kammerer and Bruce Rubidge. The generic name is from Phorcys of Greek mythology, the father of the Gorgons from which the gorgonopsians are named after, and refers to its status as one of the oldest representatives of the group in the fossil record. Phorcys was recovered from the lowest strata of the Tapinocephalus Assemblage Zone (AZ) of the Beaufort Group, making it one of the oldest known gorgonopsians in the fossil record—second only to fragmentary remains of an indeterminate gorgonopsian from the older underlying Eodicynodon Assemblage Zone.

References

  1. 1 2 3 Rubidge, B. S. (ed.) 1995b. Biostratigraphy of the Beaufort Group (Karoo Supergroup). South African Committee of Stratigraphy. Biostratigraphic Series 1. Pretoria, Council for Geoscience.
  2. 1 2 Rubidge, Bruce S.; Day, Michael O.; Barbolini, Natasha; Hancox, P. John; Choiniere, Jonah N.; Bamford, Marion K.; Viglietti, Pia A.; McPhee, Blair W.; Jirah, Sifelani (2016), "Advances in Nonmarine Karoo Biostratigraphy: Significance for Understanding Basin Development", Origin and Evolution of the Cape Mountains and Karoo Basin, Regional Geology Reviews, Springer International Publishing, pp. 141–149, doi:10.1007/978-3-319-40859-0_14, ISBN   9783319408583
  3. ↑ van der Walt, Merrill; Day, Michael; Rubidge, Bruce; Cooper, Antony; Netterberg, Inge (2010-12-31). "A new GIS-based biozone map of the Beaufort Group (Karoo Supergroup), South Africa". Palaeontologia Africana. 45: 1–6.
  4. ↑ Bain, Andrew Geddes (1845-02-01). "On the Discovery of the Fossil Remains of Bidental and other Reptiles in South Africa". Quarterly Journal of the Geological Society. 1 (1): 317–318. doi:10.1144/GSL.JGS.1845.001.01.72. hdl:2027/uc1.c034667778. ISSN   0370-291X. S2CID   128602890.
  5. ↑ Seeley, H. G. (1895). "Researches on the Structure, Organization, and Classification of the Fossil Reptilia. Part IX., Section 4. On the Gomphodontia". Philosophical Transactions of the Royal Society of London B. 186: 1–57. doi: 10.1098/rstb.1895.0001 . JSTOR   91793.
  6. ↑ Broom, R. (January 1906). "V.—On the Permian and Triassic Faunas of South Africa". Geological Magazine. 3 (1): 29–30. doi:10.1017/S001675680012271X. ISSN   1469-5081. S2CID   129265956.
  7. ↑ Day, Michael Oliver; Rubidge, Bruce Sidney (2014-12-01). "A brief lithostratigraphic review of the Abrahamskraal and Koonap formations of the Beaufort Group, South Africa: Towards a basin-wide stratigraphic scheme for the Middle Permian Karoo". Journal of African Earth Sciences. 100: 227–242. doi:10.1016/j.jafrearsci.2014.07.001. ISSN   1464-343X.
  8. 1 2 Oliver, Day, Michael (2014-03-04). Middle Permian continental biodiversity changes as reflected in the Beaufort Group of South Africa: a bio-and lithostratigraphic review of the Eodicynodon, Tapinocephalus and Pristerognathus assemblage zones (Ph.D thesis). Johannesburg: University of Witwatersrand.{{cite thesis}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Day, Michael O.; Ramezani, Jahandar; Bowring, Samuel A.; Sadler, Peter M.; Erwin, Douglas H.; Abdala, Fernando; Rubidge, Bruce S. (2015-07-22). "When and how did the terrestrial mid-Permian mass extinction occur? Evidence from the tetrapod record of the Karoo Basin, South Africa". Proc. R. Soc. B. 282 (1811): 20150834. doi:10.1098/rspb.2015.0834. ISSN   0962-8452. PMC   4528552 . PMID   26156768.
  10. ↑ Hancox, P.J; Rubidge, B.S (2001-01-01). "Breakthroughs in the biodiversity, biogeography, biostratigraphy, and basin analysis of the Beaufort group". Journal of African Earth Sciences. 33 (3–4): 563–577. doi:10.1016/S0899-5362(01)00081-1. ISSN   1464-343X.
  11. ↑ Lucas, Spencer G.; Zeigler, Kate E. (2005). The Nonmarine Permian: Bulletin 30. New Mexico Museum of Natural History and Science.
  12. ↑ Day, Mike; Rubidge, Bruce; Almond, John; Jirah, Sifelani (January 2013). "Biostratigraphic correlation in the Karoo: The case of the Middle Permian parareptile Eunotosaurus". South African Journal of Science. 109 (3–4): 4. doi: 10.1590/sajs.2013/20120030 . ISSN   0038-2353.
  13. ↑ Lyson, Tyler R.; Bever, Gabe S.; Scheyer, Torsten M.; Hsiang, Allison Y.; Gauthier, Jacques A. (2013-06-17). "Evolutionary Origin of the Turtle Shell". Current Biology. 23 (12): 1113–1119. doi: 10.1016/j.cub.2013.05.003 . ISSN   0960-9822. PMID   23727095.
  14. ↑ Botha-Brink, Jennifer; Modesto, Sean P. (2007-11-22). "A mixed-age classed 'pelycosaur' aggregation from South Africa: earliest evidence of parental care in amniotes?". Proceedings of the Royal Society of London B: Biological Sciences. 274 (1627): 2829–2834. doi:10.1098/rspb.2007.0803. ISSN   0962-8452. PMC   2288685 . PMID   17848370.
  15. ↑ Botha-Brink, Jennifer; Modesto, Sean P. (2009-06-12). "Anatomy and relationships of the Middle Permian varanopidHeleosaurus scholtzibased on a social aggregation from the Karoo Basin of South Africa". Journal of Vertebrate Paleontology. 29 (2): 389–400. doi:10.1671/039.029.0209. ISSN   0272-4634. S2CID   84703110.
  16. ↑ Modesto, Sean P.; Smith, Roger M. H.; Campione, Nicolás E.; Reisz, Robert R. (2011-10-19). "The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa". Naturwissenschaften. 98 (12): 1027–1034. doi:10.1007/s00114-011-0856-2. ISSN   0028-1042. PMID   22009069. S2CID   27865550.
  17. 1 2 Sidor, Christian (2015-04-09). "The first biarmosuchian from the upper Madumabisa Mudstone Formation (Luangwa Basin) of Zambia". Palaeontologia Africana. 49: 1–7.
  18. ↑ Kammerer, Christian F.; Smith, Roger M. H.; Day, Michael O.; Rubidge, Bruce S. (2015-02-16). "New information on the morphology and stratigraphic range of the mid-Permian gorgonopsianEriphostoma microdonBroom, 1911". Papers in Palaeontology. 1 (2): 201–221. doi:10.1002/spp2.1012. ISSN   2056-2802. S2CID   128762256.
  19. ↑ Damiani, Ross J. (2004-01-01). "Temnospondyls from the Beaufort Group (Karoo Basin) of South Africa and Their Biostratigraphy". Gondwana Research. 7 (1): 165–173. doi:10.1016/S1342-937X(05)70315-4. ISSN   1342-937X.
  20. ↑ Cisneros, Juan Carlos; Abdala, Fernando; Jashashvili, Tea; Bueno, Ana de Oliveira; Dentzien-Dias, Paula (2015-07-01). "Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana". Royal Society Open Science. 2 (7): 150090. doi:10.1098/rsos.150090. ISSN   2054-5703. PMC   4632579 . PMID   26587266.
  21. ↑ Kemp, Thomas Stainforth; Kemp, T. S. (2005). The Origin and Evolution of Mammals. OUP Oxford. ISBN   9780198507611.
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