A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes
- Coates, Michael I, Gess, Robert W, Finarelli, John A, Surname, Name - one for each creator, Criswell, Katharine E, Tietjen, Kristen
- Authors: Coates, Michael I , Gess, Robert W , Finarelli, John A , Surname, Name - one for each creator , Criswell, Katharine E , Tietjen, Kristen
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72246 , vital:30021 , https://doi.org/10.1038/nature20806
- Description: Chimaeroid fishes (Holocephali) are one of the four principal divisions of modern gnathostomes (jawed vertebrates). Despite only 47 described living species1, chimaeroids are the focus of resurgent interest as potential archives of genomic data2 and for the unique perspective they provide on chondrichthyan and gnathostome ancestral conditions. Chimaeroids are also noteworthy for their highly derived body plan1,3,4. However, like other living groups with distinctive anatomies5, fossils have been of limited use in unravelling their evolutionary origin, as the earliest recognized examples already exhibit many of the specializations present in modern forms6,7. Here we report the results of a computed tomography analysis of Dwykaselachus, an enigmatic chondrichthyan braincase from the ~280 million year old Karoo sediments of South Africa8. Externally, the braincase is that of a symmoriid shark9,10,11,12,13and is by far the most complete uncrushed example yet discovered. Internally, the morphology exhibits otherwise characteristically chimaeroid specializations, including the otic labyrinth arrangement and the brain space configuration relative to exceptionally large orbits. These results have important implications for our view of modern chondrichthyan origins, add robust structure to the phylogeny of early crown group gnathostomes, reveal preconditions that suggest an initial morpho-functional basis for the derived chimaeroid cranium, and shed new light on the chondrichthyan response to the extinction at the end of the Devonian period.
- Full Text:
- Date Issued: 2017
- Authors: Coates, Michael I , Gess, Robert W , Finarelli, John A , Surname, Name - one for each creator , Criswell, Katharine E , Tietjen, Kristen
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72246 , vital:30021 , https://doi.org/10.1038/nature20806
- Description: Chimaeroid fishes (Holocephali) are one of the four principal divisions of modern gnathostomes (jawed vertebrates). Despite only 47 described living species1, chimaeroids are the focus of resurgent interest as potential archives of genomic data2 and for the unique perspective they provide on chondrichthyan and gnathostome ancestral conditions. Chimaeroids are also noteworthy for their highly derived body plan1,3,4. However, like other living groups with distinctive anatomies5, fossils have been of limited use in unravelling their evolutionary origin, as the earliest recognized examples already exhibit many of the specializations present in modern forms6,7. Here we report the results of a computed tomography analysis of Dwykaselachus, an enigmatic chondrichthyan braincase from the ~280 million year old Karoo sediments of South Africa8. Externally, the braincase is that of a symmoriid shark9,10,11,12,13and is by far the most complete uncrushed example yet discovered. Internally, the morphology exhibits otherwise characteristically chimaeroid specializations, including the otic labyrinth arrangement and the brain space configuration relative to exceptionally large orbits. These results have important implications for our view of modern chondrichthyan origins, add robust structure to the phylogeny of early crown group gnathostomes, reveal preconditions that suggest an initial morpho-functional basis for the derived chimaeroid cranium, and shed new light on the chondrichthyan response to the extinction at the end of the Devonian period.
- Full Text:
- Date Issued: 2017
A tetrapod fauna from within the Devonian Antarctic Circle
- Gess, Robert W, Ahlberg, Per Erik Ahlberg
- Authors: Gess, Robert W , Ahlberg, Per Erik Ahlberg
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72690 , vital:30100 , https://doi.org/10.1126/science.aaq1645 , https://www.sciencemag.org/content/360/6393/1120/suppl/DC1
- Description: Until now, all known fossils of tetrapods (limbed vertebrates with digits) and near-tetrapods (such as Elpistostege, Tiktaalik, and Panderichthys) from the Devonian period have come from localities in tropical to subtropical paleolatitudes. Most are from Laurussia, a continent incorporating Europe, Greenland, and North America, with only one body fossil and one footprint locality from Australia representing the southern supercontinent Gondwana. Here we describe two previously unknown tetrapods from the Late Devonian (late Famennian) Gondwana locality of Waterloo Farm in South Africa, then located within the Antarctic Circle, which demonstrate that Devonian tetrapods were not restricted to warm environments and suggest that they may have been global in distribution.
- Full Text:
- Date Issued: 2009
- Authors: Gess, Robert W , Ahlberg, Per Erik Ahlberg
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72690 , vital:30100 , https://doi.org/10.1126/science.aaq1645 , https://www.sciencemag.org/content/360/6393/1120/suppl/DC1
- Description: Until now, all known fossils of tetrapods (limbed vertebrates with digits) and near-tetrapods (such as Elpistostege, Tiktaalik, and Panderichthys) from the Devonian period have come from localities in tropical to subtropical paleolatitudes. Most are from Laurussia, a continent incorporating Europe, Greenland, and North America, with only one body fossil and one footprint locality from Australia representing the southern supercontinent Gondwana. Here we describe two previously unknown tetrapods from the Late Devonian (late Famennian) Gondwana locality of Waterloo Farm in South Africa, then located within the Antarctic Circle, which demonstrate that Devonian tetrapods were not restricted to warm environments and suggest that they may have been global in distribution.
- Full Text:
- Date Issued: 2009
An unusual new fossil shark (Pisces: Chondrichthyes) from the Late Devonian of South Africa
- Anderson, M Eric, Long, John A, Gess, Robert W, Hiller, Norton
- Authors: Anderson, M Eric , Long, John A , Gess, Robert W , Hiller, Norton
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73910 , vital:30240 , http://museum.wa.gov.au/sites/default/files/10. Anderson, Long, Gess, Hiller.pdf
- Description: A new stem-group chondrichthyan fish, PlesioselacJllIs macracanthlls gen. et sp. nov., is described from the Late Devonian Witpoort Formation, representing an estuarine lagoon site, near Grahamstown, South Africa. Based on a single, fairly complete specimen, it is distinctive in its a single dorsal fin braced by a large, stout spine with numerous ribs and posterior denticles, apparently no second dorsal or anal fin, an amphistylic jaw suspension, and a distinctive triangular palatoquadrate. It is suggested that the species may represent a high-latitude, Late Devonian relict taxon.
- Full Text:
- Date Issued: 1999
- Authors: Anderson, M Eric , Long, John A , Gess, Robert W , Hiller, Norton
- Date: 1999
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73910 , vital:30240 , http://museum.wa.gov.au/sites/default/files/10. Anderson, Long, Gess, Hiller.pdf
- Description: A new stem-group chondrichthyan fish, PlesioselacJllIs macracanthlls gen. et sp. nov., is described from the Late Devonian Witpoort Formation, representing an estuarine lagoon site, near Grahamstown, South Africa. Based on a single, fairly complete specimen, it is distinctive in its a single dorsal fin braced by a large, stout spine with numerous ribs and posterior denticles, apparently no second dorsal or anal fin, an amphistylic jaw suspension, and a distinctive triangular palatoquadrate. It is suggested that the species may represent a high-latitude, Late Devonian relict taxon.
- Full Text:
- Date Issued: 1999
Kowieria alveoformis gen. nov. sp. nov., a new heterosporous lycophyte from the Latest Devonian of Southern Africa
- Gess, Robert W, Prestianni, Cyrille
- Authors: Gess, Robert W , Prestianni, Cyrille
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73894 , vital:30239 , https://doi.org/10.1016/j.revpalbo.2017.10.002
- Description: A new lycopsid, Kowieria alveoformis gen. et sp. nov., is described from the FamennianWitpoort Formation, Grahamstown, South Africa. It possesses spirally arranged elongated falcate vegetative leaves. Terminal bisporangiate strobili are present and show loosely grouped micro- and megasporophylls. Sporophylls are similar in shape to the vegetative leaves though somewhat wider with a marked expansion to house the sporangium. One sporangium is attached directly to the adaxial surface of the lamina. Each megasporangium contains up to four heavily ornamented hologulate megaspores of the Lagenicula type. The combination of both basal and derived characters within this plant places it at an interesting position at the base of the phylogenetic tree of rhizomorphic lycopsids.
- Full Text:
- Date Issued: 2018
- Authors: Gess, Robert W , Prestianni, Cyrille
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73894 , vital:30239 , https://doi.org/10.1016/j.revpalbo.2017.10.002
- Description: A new lycopsid, Kowieria alveoformis gen. et sp. nov., is described from the FamennianWitpoort Formation, Grahamstown, South Africa. It possesses spirally arranged elongated falcate vegetative leaves. Terminal bisporangiate strobili are present and show loosely grouped micro- and megasporophylls. Sporophylls are similar in shape to the vegetative leaves though somewhat wider with a marked expansion to house the sporangium. One sporangium is attached directly to the adaxial surface of the lamina. Each megasporangium contains up to four heavily ornamented hologulate megaspores of the Lagenicula type. The combination of both basal and derived characters within this plant places it at an interesting position at the base of the phylogenetic tree of rhizomorphic lycopsids.
- Full Text:
- Date Issued: 2018
New morphological information on, and species of placoderm fish Africanaspis (Arthrodira, Placodermi) from the Late Devonian of South Africa
- Gess, Robert W, Trinajstic, Kate M
- Authors: Gess, Robert W , Trinajstic, Kate M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72701 , vital:30101 , https://doi.org/10.1371/journal.pone.0173169
- Description: Here we present a new species of placoderm fish, Africanaspis edmountaini sp. nov., and redescribe Africanaspis doryssa on the basis of new material collected from the type locality of Africanaspis. The new material includes the first head shields of Africanaspis doryssa in addition to soft anatomy for both taxa. Hitherto Africanaspis was entirely described from trunk armour and no record of body and fin outlines had been recorded. In addition the first record of embryonic and juvenile specimens of Africanaspis doryssa is presented and provides a growth series from presumed hatchlings to presumed adults. The presence of a greater number of juveniles compared to adults indicates that the Waterloo Farm fossil site in South Africa represents the first nursery site of arthrodire placoderms known from a cold water environment. The preservation of an ontogenetic series demonstrates that variation within the earlier known sample, initially considered to have resulted from ontogenetic change, instead indicates the presence of a second, less common species Africanaspis edmountaini sp. nov. There is some faunal overlap between the Waterloo Farm fossil site and faunas described from Strud in Belgium and Red Hill, Pennsylvania, in north America, supporting the concept of a more cosmopolitan vertebrate fauna in the Famennian than earlier in the Devonian.
- Full Text:
- Date Issued: 2017
- Authors: Gess, Robert W , Trinajstic, Kate M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/72701 , vital:30101 , https://doi.org/10.1371/journal.pone.0173169
- Description: Here we present a new species of placoderm fish, Africanaspis edmountaini sp. nov., and redescribe Africanaspis doryssa on the basis of new material collected from the type locality of Africanaspis. The new material includes the first head shields of Africanaspis doryssa in addition to soft anatomy for both taxa. Hitherto Africanaspis was entirely described from trunk armour and no record of body and fin outlines had been recorded. In addition the first record of embryonic and juvenile specimens of Africanaspis doryssa is presented and provides a growth series from presumed hatchlings to presumed adults. The presence of a greater number of juveniles compared to adults indicates that the Waterloo Farm fossil site in South Africa represents the first nursery site of arthrodire placoderms known from a cold water environment. The preservation of an ontogenetic series demonstrates that variation within the earlier known sample, initially considered to have resulted from ontogenetic change, instead indicates the presence of a second, less common species Africanaspis edmountaini sp. nov. There is some faunal overlap between the Waterloo Farm fossil site and faunas described from Strud in Belgium and Red Hill, Pennsylvania, in north America, supporting the concept of a more cosmopolitan vertebrate fauna in the Famennian than earlier in the Devonian.
- Full Text:
- Date Issued: 2017
Oldest known naiaditid bivalve from the high-latitude Late Devonian (Famennian) of South Africa offers clues to survival strategies following the Hangenberg mass extinction
- Scholze, Frank, Gess, Robert W
- Authors: Scholze, Frank , Gess, Robert W
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73921 , vital:30241 , https://doi.org/10.1016/j.palaeo.2017.01.018
- Description: A phased mass extinction event (which culminated in the Hangenberg event) marked the end of the Devonian period and had a significant impact on the palaeoecology and faunal diversity of vertebrate and invertebrate communities. In the present study the taxonomy of bivalves from the Waterloo Farm lagerstätte of the Upper Devonian, Famennian, Witpoort Formation (Witteberg Group, Cape Supergroup) was studied and compared with known Carboniferous examples. For the first time, Devonian bivalves of the Naiaditidae are described from a high-latitude palaeogeographic setting of Gondwana. The presented data suggests a high-latitude origin for post-Hangenberg event Naiaditidae, found at lower latitudes during the Early Carboniferous. This may have resulted from migration to lower latitudes in response to reduced global temperatures, which were associated with climatic perturbation at the time of the Hangenberg event, and which persisted into the Early Carboniferous. Taxa that were adapted to temperature ranges existing at high latitudes during the Late Devonian are likely to have followed these temperature ranges towards lower latitudes with decreasing global temperatures. Here they may have occupied free ecospace available in the aftermath of the Late Devonian extinction event.
- Full Text:
- Date Issued: 2017
- Authors: Scholze, Frank , Gess, Robert W
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73921 , vital:30241 , https://doi.org/10.1016/j.palaeo.2017.01.018
- Description: A phased mass extinction event (which culminated in the Hangenberg event) marked the end of the Devonian period and had a significant impact on the palaeoecology and faunal diversity of vertebrate and invertebrate communities. In the present study the taxonomy of bivalves from the Waterloo Farm lagerstätte of the Upper Devonian, Famennian, Witpoort Formation (Witteberg Group, Cape Supergroup) was studied and compared with known Carboniferous examples. For the first time, Devonian bivalves of the Naiaditidae are described from a high-latitude palaeogeographic setting of Gondwana. The presented data suggests a high-latitude origin for post-Hangenberg event Naiaditidae, found at lower latitudes during the Early Carboniferous. This may have resulted from migration to lower latitudes in response to reduced global temperatures, which were associated with climatic perturbation at the time of the Hangenberg event, and which persisted into the Early Carboniferous. Taxa that were adapted to temperature ranges existing at high latitudes during the Late Devonian are likely to have followed these temperature ranges towards lower latitudes with decreasing global temperatures. Here they may have occupied free ecospace available in the aftermath of the Late Devonian extinction event.
- Full Text:
- Date Issued: 2017
Rinistachya hilleri gen. et sp. nov.(Sphenophyllales), from the upper Devonian of South Africa
- Prestianni, Cyrille, Gess, Robert W
- Authors: Prestianni, Cyrille , Gess, Robert W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73883 , vital:30238 , https://doi.org/10.1007/s13127-018-0385-3
- Description: A rich and diverse plant assemblage has been excavated from latest Devonian (Famennian) black shales of the Witpoort Formation (Witteberg Group) at Waterloo Farm, close to the city of Grahamstown (South Africa). Several specimens of a new sphenopsid have been collected. The description of this as a new taxon, here named Rinistachya hilleri, gen. et sp. nov., provides an important addition to the scarce early record of the group. Rinistachya hilleri presents a novel architecture that include apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia). Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales. Rinistachya furthermore represents the first record of a Devonian sphenopsid from Gondwana and extends the known distribution of the Sphenopsida from the tropics to very high palaeolatitudes. It is a new sphenopsid with a peculiar organisation. The new taxon allows better characterization of the initial evolutionary radiation at the base of the group.
- Full Text:
- Date Issued: 2018
- Authors: Prestianni, Cyrille , Gess, Robert W
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73883 , vital:30238 , https://doi.org/10.1007/s13127-018-0385-3
- Description: A rich and diverse plant assemblage has been excavated from latest Devonian (Famennian) black shales of the Witpoort Formation (Witteberg Group) at Waterloo Farm, close to the city of Grahamstown (South Africa). Several specimens of a new sphenopsid have been collected. The description of this as a new taxon, here named Rinistachya hilleri, gen. et sp. nov., provides an important addition to the scarce early record of the group. Rinistachya hilleri presents a novel architecture that include apparently plesiomorphic characters, reminiscent of the organisation of the Iridopteridales (including the production of two types of laterals at one node, the location of fertile parts in loose whorls on lateral branches and an organisation of the fertile parts in which they branch several times before bearing distally elongate sporangia). Other characters unambiguously nest Rinistachya within the Sphenopsida (including presence of planate and slightly webbed ultimate appendages and lateral strobili made of successive whorls of fertile leaves with fertile parts located at their axil). This provides strong support for a close relationship between Sphenopsida and Iridopteridales. Rinistachya furthermore represents the first record of a Devonian sphenopsid from Gondwana and extends the known distribution of the Sphenopsida from the tropics to very high palaeolatitudes. It is a new sphenopsid with a peculiar organisation. The new taxon allows better characterization of the initial evolutionary radiation at the base of the group.
- Full Text:
- Date Issued: 2018
The first Bothriolepsis-associated Devonian fish fauna from Africa
- Anderson, M Eric, Hiller, Norton, Gess, Robert W
- Authors: Anderson, M Eric , Hiller, Norton , Gess, Robert W
- Date: 1994
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73852 , vital:30235 , https://journals.co.za/content/sajsci/90/7/AJA00382353_5900
- Description: An advanced diplacanthid (Climatiiformes) is described from a Famennian estuarine environment of South Africa. It is characterized by having exceptionally long thin fin spines and a deep body form. Unusual details of the fins and fin spine insertions are preserved. This is the first record of a diplacanthid from the Southern Hemisphere.
- Full Text:
- Date Issued: 1994
- Authors: Anderson, M Eric , Hiller, Norton , Gess, Robert W
- Date: 1994
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/73852 , vital:30235 , https://journals.co.za/content/sajsci/90/7/AJA00382353_5900
- Description: An advanced diplacanthid (Climatiiformes) is described from a Famennian estuarine environment of South Africa. It is characterized by having exceptionally long thin fin spines and a deep body form. Unusual details of the fins and fin spine insertions are preserved. This is the first record of a diplacanthid from the Southern Hemisphere.
- Full Text:
- Date Issued: 1994
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