caa a22 4500 388110481 CHVBK 20180307125352.0 cr unu---uuuuu 161130s1999 xx s 000 0 eng 10.1017/S0263593300002558 doi S0263593300002558 pii (NATIONALLICENCE)cambridge-10.1017/S0263593300002558 The tuning fork graptoloid, Didymograptus murchisoni (Beck, 1839) [Elektronische Daten] The development of D. (Didymograptus) murchisoni (Beck), the type species of the genus, is shown to be unequivocally of anus type, with thl1 dicalyal and a low metasicular origin of thl1. An evolutionary line from the early, Arenig, bifidus group is supported; and clear distinctions are drawn between the subgenera D. (Didymograptus), D. (Didymograptellus) and D. (Jenkinsograptus), the first of these being redefined. The range of variation of biocharacters of D. murchisoni is analysed using exquisitely preserved undeformed material from Saudi Arabia, and comparisons are made with the undeformed type material, and with undeformed (nodule) collections from Abereiddy Bay, Pembrokeshire. The astogenetically late developments of D. murchisoni are described. Copyright © Royal Society of Edinburgh 1999 astogeny nationallicence graptolites nationallicence Rickards R. B. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K. Khashogji M. S. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K. Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/3(1999), 173-187 0263-5933 90:3<173 1999 90 TRE https://doi.org/10.1017/S0263593300002558 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0263593300002558 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Rickards R. B. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K NATIONALLICENCE 700 1- Khashogji M. S. Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, U.K NATIONALLICENCE 773 0- Transactions of the Royal Society of Edinburgh: Earth Sciences Royal Society of Edinburgh Scotland Foundation 90/3(1999), 173-187 0263-5933 90:3<173 1999 90 TRE CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge