Pub Date : 1978-09-11DOI: 10.1017/S0080456800012898
J. R. F. Dick
Synopsis Skeletal remains of Tristychius arcuatus commonly occur in ironstone nodules from the Scottish Upper and Lower Oil Shale Groups. This material is clearly distinguishable from the small shark from Glencartholm described by Traquair, Woodward and Moy-Thomas under this name. Study of the latter shows that its finspines are distinctly different from the holotype of T. arcuatus and, therefore, it has been renamed. Tristychius arcuatus sensu stricto is a medium-sized hybodont shark with a short gape, a functionally heterocercal tail and narrow-based, tribasal pectoral fins. Its most unusual feature is a well developed opercular gill cover composed of long hyoid rays. Evidence suggests that this character was present in several Palaeozoic sharks, although it is absent in all Recent elasmobranchs. It is not clear whether it was primitively present in chondrichthyans or evolved separately in several lineages. Hybodonts and ctenacanths are recognised as separate, specialised shark radiations, neither of which can be directly ancestral to Recent sharks. Of the two, hybodonts appear to be more closely related to Recent forms, although the presence of typical hybodont finspines in Tristychius arcuatus indicates that they had diverged from ancestral euselachians before the beginning of the Carboniferous.
{"title":"On the Carboniferous shark Tristychius arcuatus Agassiz from Scotland","authors":"J. R. F. Dick","doi":"10.1017/S0080456800012898","DOIUrl":"https://doi.org/10.1017/S0080456800012898","url":null,"abstract":"Synopsis Skeletal remains of Tristychius arcuatus commonly occur in ironstone nodules from the Scottish Upper and Lower Oil Shale Groups. This material is clearly distinguishable from the small shark from Glencartholm described by Traquair, Woodward and Moy-Thomas under this name. Study of the latter shows that its finspines are distinctly different from the holotype of T. arcuatus and, therefore, it has been renamed. Tristychius arcuatus sensu stricto is a medium-sized hybodont shark with a short gape, a functionally heterocercal tail and narrow-based, tribasal pectoral fins. Its most unusual feature is a well developed opercular gill cover composed of long hyoid rays. Evidence suggests that this character was present in several Palaeozoic sharks, although it is absent in all Recent elasmobranchs. It is not clear whether it was primitively present in chondrichthyans or evolved separately in several lineages. Hybodonts and ctenacanths are recognised as separate, specialised shark radiations, neither of which can be directly ancestral to Recent sharks. Of the two, hybodonts appear to be more closely related to Recent forms, although the presence of typical hybodont finspines in Tristychius arcuatus indicates that they had diverged from ancestral euselachians before the beginning of the Carboniferous.","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1978-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87999752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-01-01DOI: 10.1017/s0080456800012886
{"title":"TRE volume 70 issue 4 Cover and Back matter","authors":"","doi":"10.1017/s0080456800012886","DOIUrl":"https://doi.org/10.1017/s0080456800012886","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1978-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74338013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1978-01-01DOI: 10.1017/s0080456800012874
{"title":"TRE volume 70 issue 4 Cover and Front matter","authors":"","doi":"10.1017/s0080456800012874","DOIUrl":"https://doi.org/10.1017/s0080456800012874","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1978-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89278173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015209
D. Edwards
Synopsis New collections of Zosterophyllum myretonianum Penhallow have been made at a number of localities in the Lower Old Red Sandstone of Scotland. For the first time, details of the fructification are recorded and incorporated into an emended diagnosis of the species. A comparison with the remaining species of Zosterophyllum indicates that sporangial and stalk characteristics are most important in delimiting Z. myretonianum. Tentative explanations for the wide variation in the overall morphology of the fructifications are put forward.
{"title":"11.—Some Observations on the Fertile Parts of Zosterophyllum myretonianum Penhallow from the Lower Old Red Sandstone of Scotland","authors":"D. Edwards","doi":"10.1017/S0080456800015209","DOIUrl":"https://doi.org/10.1017/S0080456800015209","url":null,"abstract":"Synopsis New collections of Zosterophyllum myretonianum Penhallow have been made at a number of localities in the Lower Old Red Sandstone of Scotland. For the first time, details of the fructification are recorded and incorporated into an emended diagnosis of the species. A comparison with the remaining species of Zosterophyllum indicates that sporangial and stalk characteristics are most important in delimiting Z. myretonianum. Tentative explanations for the wide variation in the overall morphology of the fructifications are put forward.","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87934946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015192
{"title":"TRE volume 69 issue 11 Cover and Back matter","authors":"","doi":"10.1017/S0080456800015192","DOIUrl":"https://doi.org/10.1017/S0080456800015192","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74500817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015234
J. G. Long
Synopsis Twenty-eight specimens of the seed genus Dolichosperma have been examined. Fourteen are assigned to D. sexangulatum Long; these possess six or seven integumental lobes which extend apically as free tentacles equal in length to the seed body except when damaged or broken off. Fourteen other specimens are named D. pentagonum sp. nov. These are smaller and usually have five integumental lobes (less commonly six or seven). Long apical tentacles have not been seen in this species. Evidence is adduced that Anasperma burnense Long is the mature prothallial seed developed from the ovule Eurystoma trigona Long. Eurystoma angulare Long sometimes possesses five integumental lobes and the free apical lobes vary in length. Compressed megaspores macerated from cupules of Stamnostoma huttonense Long sometimes have three abortive spores in a compact group at the apex. Ovules of Eccroustosperma langtonense Long were borne in small bunches (probably pendent) on short pedicels; one specimen of this seed shows three well-developed separate abortive spores around the apex of the functional megaspore. The cupule of Calathospermum fimbriatum Barnard shows a structure suggesting that it may have evolved from a pair of cupules. Twelve to fourteen ovules were sometimes formed in the entire cupule though most of these were probably abortive. Some possible seed embryos are described and discussed, and an outline classification of seeds in the order Lagenostomales is proposed.
{"title":"12.—Further Observations on some Lower Carboniferous Seeds and Cupules","authors":"J. G. Long","doi":"10.1017/S0080456800015234","DOIUrl":"https://doi.org/10.1017/S0080456800015234","url":null,"abstract":"Synopsis Twenty-eight specimens of the seed genus Dolichosperma have been examined. Fourteen are assigned to D. sexangulatum Long; these possess six or seven integumental lobes which extend apically as free tentacles equal in length to the seed body except when damaged or broken off. Fourteen other specimens are named D. pentagonum sp. nov. These are smaller and usually have five integumental lobes (less commonly six or seven). Long apical tentacles have not been seen in this species. Evidence is adduced that Anasperma burnense Long is the mature prothallial seed developed from the ovule Eurystoma trigona Long. Eurystoma angulare Long sometimes possesses five integumental lobes and the free apical lobes vary in length. Compressed megaspores macerated from cupules of Stamnostoma huttonense Long sometimes have three abortive spores in a compact group at the apex. Ovules of Eccroustosperma langtonense Long were borne in small bunches (probably pendent) on short pedicels; one specimen of this seed shows three well-developed separate abortive spores around the apex of the functional megaspore. The cupule of Calathospermum fimbriatum Barnard shows a structure suggesting that it may have evolved from a pair of cupules. Twelve to fourteen ovules were sometimes formed in the entire cupule though most of these were probably abortive. Some possible seed embryos are described and discussed, and an outline classification of seeds in the order Lagenostomales is proposed.","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90701441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015179
P. Barnard, J. G. Long
Synopsis Triradioxylon gen. nov. is erected for petrified stems and petioles in which the primary xylem has a triradiate form and possesses protoxylem at the ends of the arms and in the central region. Secondary xylem is dense and composed of small tracheids having multiseriate bordered pits on all walls. Rays are narrow and high. The cortex has sclerotic nests and radial bands of fibres (sparganum structure). In the type species T. primaevum sp. nov. the petioles are borne 5–6 cm apart in a phyllotactic spiral of ⅓ on a stem about 1 cm (or more) diameter. The petiole is swollen at its base (about 8 mm diameter) and very gradually tapers to about 2 mm in the rachis which has not been seen to dichotomise. The length of petiole up to the first pinna may exceed 10 cm. Pinnae arose alternately and themselves branched. The T-shaped petiolar bundle has two protoxylem groups at the end of each arm and the central protoxylem divided into three in the rachis. Two detached rachises which cannot be assigned with certainty to Triradioxylon primaevum are placed in the genus Lyginorachis and named L. whitadderensis sp. nov. In these the T-shaped vascular bundle is slightly larger than that in the rachises of T. primaevum and the ends of the transverse arms are wider and may possess three protoxylem groups. The rachises in both T.primaevum and L. whitadderensis bear alternate triarch pinna-traces but in L. whitadderensis a pair of sub-opposite monarch pinna-traces is also present. Triradioxylon is classified along with Buteoxylon in the family Buteoxylonaceae placed tentatively as incertae sedis in the Pteridosperms although showing some affinity with Aneurophyton in the Progymnospermopsida.
{"title":"10.—Triradioxylon—a New Genus of Lower Carboniferous Petrified Stems and Petioles together with a Review of the Classification of Early Pterophytina","authors":"P. Barnard, J. G. Long","doi":"10.1017/S0080456800015179","DOIUrl":"https://doi.org/10.1017/S0080456800015179","url":null,"abstract":"Synopsis Triradioxylon gen. nov. is erected for petrified stems and petioles in which the primary xylem has a triradiate form and possesses protoxylem at the ends of the arms and in the central region. Secondary xylem is dense and composed of small tracheids having multiseriate bordered pits on all walls. Rays are narrow and high. The cortex has sclerotic nests and radial bands of fibres (sparganum structure). In the type species T. primaevum sp. nov. the petioles are borne 5–6 cm apart in a phyllotactic spiral of ⅓ on a stem about 1 cm (or more) diameter. The petiole is swollen at its base (about 8 mm diameter) and very gradually tapers to about 2 mm in the rachis which has not been seen to dichotomise. The length of petiole up to the first pinna may exceed 10 cm. Pinnae arose alternately and themselves branched. The T-shaped petiolar bundle has two protoxylem groups at the end of each arm and the central protoxylem divided into three in the rachis. Two detached rachises which cannot be assigned with certainty to Triradioxylon primaevum are placed in the genus Lyginorachis and named L. whitadderensis sp. nov. In these the T-shaped vascular bundle is slightly larger than that in the rachises of T. primaevum and the ends of the transverse arms are wider and may possess three protoxylem groups. The rachises in both T.primaevum and L. whitadderensis bear alternate triarch pinna-traces but in L. whitadderensis a pair of sub-opposite monarch pinna-traces is also present. Triradioxylon is classified along with Buteoxylon in the family Buteoxylonaceae placed tentatively as incertae sedis in the Pteridosperms although showing some affinity with Aneurophyton in the Progymnospermopsida.","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78565529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015180
{"title":"TRE volume 69 issue 11 Cover and Front matter","authors":"","doi":"10.1017/S0080456800015180","DOIUrl":"https://doi.org/10.1017/S0080456800015180","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84137012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015258
{"title":"TRE volume 69 issue 13 Cover and Back matter","authors":"","doi":"10.1017/S0080456800015258","DOIUrl":"https://doi.org/10.1017/S0080456800015258","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79586627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1975-01-01DOI: 10.1017/S0080456800015210
{"title":"TRE volume 69 issue 12 Cover and Front matter","authors":"","doi":"10.1017/S0080456800015210","DOIUrl":"https://doi.org/10.1017/S0080456800015210","url":null,"abstract":"","PeriodicalId":23232,"journal":{"name":"Transactions of the Royal Society of Edinburgh","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1975-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76089007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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