Graptoloidea

Rhabdinopora flabelliformis anglica, copyright Gennadi Baranov.

Belongs within: Dendroidea.
Contains: Eugraptoloida.

The Graptoloidea are the clade including the planktic graptolites, characterised by the possession of a nematophorous sicula with a free nema in the adult stage (Maletz et al. 2009).

The writing in the rocks
Published 24 October 2007
Rhabdinopora, from here.

I’m probably showing unbelievable levels of geekiness in saying so, but I have a certain degree of affection for graptolites. They were one of first examples I became aware of as a lad of a completely extinct lineage of fossil organisms of uncertain relationships to anything alive today. Graptolites were an abundant group of colonial animals in the Palaeozoic. The name Graptolithus can be translated from Latin as “rock with writing”, and was originally coined by Linnaeus for what he thought were mineralisations of inorganic origin (Linnaeus’ original classification covered minerals as well as plants and animals).

The most speciose lineage of graptolites, the Graptoloidea, was planktonic but other orders of graptolites were sessile and benthic. Most modern authors agree that the graptolites were closely related to the pterobranchs, a small group of modern colonial animals (both in the sense of not including many species, and in being small in size). The story of how the relationship between graptolites and pterobranchs came to be recognised is an interesting one in its own right. Critical well-preserved specimens of early sessile graptolites were described by Roman Kozłowski from the Holy Cross Mountains in Poland (Kozłowski 1949) but the results of his research almost never saw the light of day due to the minor inteference of the Second World War.

As I’ve already indicated, the earliest graptolites were benthic, and one of the most successful benthic orders were the Dendroidea, so-called because of their multi-branching tree-like structure. The Graptoloidea were derived from dendroid-type ancestors, and basal graptoloids such as Rhabdinopora can essentially be described as a dendroid detached from the bottom and hung upside down. Many popular books will then go on, as I am about to, to describe the subsequent history of graptoloids in a misleadingly linear way. However, the dendroids did not disappear with the rise of the graptoloids, though they never achieved the diversity of the latter. In fact, the dendroids survived long after the graptoloids had fallen by the wayside. Dendroids were still alive and well in the early Carboniferous whereas graptoloids never made it past the Devonian.

Spirograptus turriculatus, from the University of Oslo.

Nevertheless, as time went by the early multi-branched planktonic forms gave way to descendents with a far simpler organisation. Four-branched taxa gave rise to two-branched taxa, which in turn gave way to the linear monograptids. Another group of graptoloids, the retiolitids, took a different approach to lightening the colony structure, and reduced the colonial wall to a minimalist net-like framework (Kozłowska-Dawidziuk 2004—I’d recommend taking a look at this article, especially if, like me, you’ve had some difficulty in imaging retiolitids as live animals).

Graptoloids are a very useful group of organisms for biostratigraphy, combining the ideal features of wide distribution of individual species with relatively rapid species turnover. Biostratigraphy is the main focus of Zhang & Lenz’s (1997) paper. The Ludlow epoch was in the later Silurian and the fauna described by Zhang & Lenz consists entirely of monograptids and retiolitids, the only graptoloid groups to survive the end of the preceeding Wenlock epoch. There’s not much to say about this paper—it’s a fairly standard example of a faunal survey, describing the graptolites found in the Shuiqingliangzi section in southern China. No new taxa were described, though detailed redescriptions were given of a number of taxa.

Systematics of Graptoloidea
<==Graptoloidea [Anisograptidae, Graptodendroidina, Graptolitidae, Graptoloida, Rhabdinoporinae, Rhabdophora, Tetragrapti]
    |--Radiograptus Bulman 1950FC86, M14
    |    `--*R. rosieranus Bulman 1950B70
    `--+--Staurograptus Emmons 1855FC86, FEZ05 (see below for synonymy)
       |    |--*S. dichotomus Emmons 1855 (see below for synonymy)FEZ05
       |    |--S. apertus Ruedemann 1904 [=S. dichotomus var. apertus]FEZ05
       |    `--S. hyperboreus (Obut & Sobolevskaya 1962) (see below for synonymy)FEZ05
       `--+--Rhabdinopora Eichwald 1855FC86, B70 (see below for synonymy)
          |    |--*R. flabelliformis (Eichwald 1840)B70 (see below for synonymy)
          |    |    |--R. f. flabelliformisFEZ05
          |    |    |--R. f. anglicaFEZ05
          |    |    |--‘Dictyonema flabelliforme’ norvegicumB70
          |    |    `--R. f. parabola [incl. Staurograptus dichotomus priscus Lin 1986]FEZ05
          |    |--R. desmograptoidesWC04
          |    |--R. dichotomusWC04
          |    |--*Ceramites’ hisingeri Liebmann in Forchhammer 1845H62
          |    |--R. praeparabolaFEZ05
          |    |--R. scitulumWC04
          |    `--R. socialis (Salter 1858)WC04, B70 [=*Graptopora socialisB70, Dictyonema flabelliforme socialeB70]
          `--+--AnisograptinaeFC86
             |    |--Triograptus Monsen 1925FC86, B70
             |    |    |--*T. osloensis Monsen 1925B70
             |    |    `--T. canadensisB70
             |    `--Anisograptus Ruedemann 1937B70
             |         |--*A. matanensis Ruedemann 1937B70
             |         |    |--A. m. matanensisFEZ05
             |         |    `--A. m. tetragraptoidesFEZ05
             |         |--A. flexuosusB70
             |         `--A. richardsoniFEZ05
             `--Adelograptinae [Didymograpta, Didymograptina]FC86
                  |--EugraptoloidaFC86
                  `--+--Kiaerograptus Spjeldnaes 1963FC86, B70
                     |    |--*K. kiaeri (Monsen 1925) [=Didymograptus kiaeri]B70
                     |    `--K. supremusM14
                     `--Adelograptus Bulman 1941FC86, B70 [incl. Choristograptus Legrand 1964B70, M14]
                          |--*A. hunnebergensis (Moberg 1892) [=Bryograptus hunnebergensis]B70
                          |--A. antiquusR93
                          |--A. asiaticusCT83
                          |--A. clarkiC68
                          |--A. lapworthiB70
                          |--*Choristograptus’ louhai Legrand 1963B70
                          |--A. sinicusCT83
                          |--A. tenellus (Linnarsson 1871)MCM09
                          `--A. victoriaeC68
Graptoloidea incertae sedis:
  Psigraptus Jackson 1967B70
    `--*P. arcticus Jackson 1967B70
  Araneograptus Erdtmann & VandenBerg 1985M14
    |--A. macgillivrayiWC04
    |--A. murrayiWC04
    `--A. pulchellusWC04
  Ancoragraptus Jackson & Lenz 2003M14
  Aorograptus Williams & Stevens 1991M14
  Bryograptus Lapworth 1880M14
    |--*B. kjerulfi Lapworth 1880B70
    |--B. matanensis [incl. B. matanensis var. tetragraptoides]CT83
    `--B. patensB70
  Chigraptus Jackson & Lenz 1999M14
  Damesograptus Jahn 1892M14
  Diphygraptus Zhao & Zhang 1985M14
  Heterograptus Zhao & Zhang in Lin 1986M14
  Holopsigraptus Zhao & Zhang 1985M14
  Hunjiangograptus Zhao & Zhang 1985M14
  Hunnegraptus Lindholm 1991M14
    `--H. copiosusMCM09
  Muenzhigraptus Zhao & Zhang 1985M14
  Neoclonograptus Zhao & Zhang 1985M14
  Nephelograptus Ruedemann 1947M14
    `--*N. rectibrachiatus Ruedemann 1947B70
  Paraclonograptus Zhao & Zhang 1985M14
  Paratemnograptus Williams & Stevens 1991M14
  Sagenograptus Obut & Sobolevskaya 1962M14
    |--*S. gagarini Obut & Sobolevskaya 1962B70
    `--S. arctos Lenz & Kozłowska-Dawidziuk 2001K-D04
  Stellatograptus Erdtmann 1967M14
    `--*S. stellatus Erdtmann 1967B70
  Toyenograptus Li 1984M14
  Triramograptus Erdtmann in Cooper et al. 1998M14
    `--T. atavusFEZ05
  Yukonograptus Lin 1981M14

Rhabdinopora Eichwald 1855FC86, B70 [=Dictyograptus Westergård 1909 non Hopkinson 1875B70, Phyllograpta Angelin 1854B70; incl. Ceramites Liebmann in Forchhammer 1845H62, Graptopora Salter 1858B70]

*Rhabdinopora flabelliformis (Eichwald 1840)B70 [=Gorgonia flabelliformisB70, *Dictyograptus flabelliformisB70, Dictyonema flabelliformeFC86, *Phyllograpta flabelliformisB70; incl. Dictyonema flabelliforme var. confertaK49]

Staurograptus Emmons 1855FC86, FEZ05 [=StaurograpsusFEZ05; incl. Aletograptus Obut & Sobolevskaya 1962FEZ05; Staurograptinae]

*Staurograptus dichotomus Emmons 1855 [incl. S. borealis Zhao 1983, S. dasycladus Zhao 1983, Radiograptus rosieranus flexibilis Fortey in Fortey et al. 1982, S. (Radiograptus) flexibilis, S. immaturus Wang, Liu & Zhou 1979, S. dichotomus immaturus, S. magnus Yu, Liu & Fang 1984, S. minimus Mu in Mu & Lin 1984, S. orientalis Mu in Mu & Lin 1984, S. dichotomus sinicus Mu in Mu & Lin 1984, S. taishanensis Wang, Liu & Zhou 1979, S. dichotomus taishanensis, S. tenuis tangpanensis Yu, Liu & Fang 1984, S. tenuis Jackson 1974]FEZ05

Staurograptus hyperboreus (Obut & Sobolevskaya 1962) [=*Aletograptus hyperboreus; incl. A. flexibilis Yu, Liu & Fang 1984, A. incertus Yu, Liu & Fang 1984, Triograptus rigidus Yu, Liu & Fang 1984]FEZ05

*Type species of generic name indicated

References

[B70] Bulman, O. M. B. 1970. Graptolithina with sections on Enteropneusta and Pterobranchia. In: Teichert, C. (ed.) Treatise on Invertebrate Paleontology pt V 2nd ed. pp. V1–V149. The Geological Society of America, Inc.: Boulder (Colorado), and the University of Kansas: Lawrence (Kansas).

[CT83] Chen J.-Y. & C. Teichert. 1983. Cambrian Cephalopoda of China. Palaeontographica Abteilung A: Paläozoologie—Stratigraphie 181 (1–3): 1–102.

[C68] Cooper, R. A. 1968. Lower and Middle Paleozoic fossil localities of north-west Nelson. Transactions of the Royal Society of New Zealand, Geology 6 (7): 75–89.

[FEZ05] Feng, H., B.-D. Erdtmann & Y. Zhang. 2005. Taxonomy and phylogeny of Staurograptus Emmons from the base of the Ordovician. Palaeontology 48 (5): 1007–1019.

[FC86] Fortey, R. A., & R. A. Cooper. 1986. A phylogenetic classification of the graptoloids. Palaeontology 29: 631–654.

[H62] Häntzschel, W. 1962. Trace fossils and problematica. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt W. Miscellanea: Conodonts, Conoidal Shells of Uncertain Affinities, Worms, Trace Fossils and Problematica pp. W177–W245. Geological Society of America, and University of Kansas Press.

[K-D04] Kozłowska-Dawidziuk, A. 2004. Evolution of retiolitid graptolites—a synopsis. Acta Palaeontologica Polonica 49 (4): 505–518.

[K49] Kozłowski, R. 1949. Les graptolithes et quelques nouveaux groupes d’animaux du Tremadoc de la Pologne. Palaeontologica Polonica 3:i–xii, 1–235.

[M14] Maletz, J. 2014. The classification of the Pterobranchia (Cephalodiscida and Graptolithina). Bulletin of Geosciences 89 (3): 477–540.

[MCM09] Maletz, J., J. Carlucci & C. E. Mitchell. 2009. Graptoloid cladistics, taxonomy and phylogeny. Bulletin of Geosciences 84 (1): 7–19.

[R93] Rickards, R. B. 1993. Graptolithina. In: Benton, M. J. (ed.) The Fossil Record 2 pp. 537–542. Chapman & Hall: London.

[WC04] Webby, B. D., R. A. Cooper, S. M. Bergström & F. Paris. 2004. Stratigraphic framework and time slices. In: Webby, B. D., F. Paris, M. L. Droser & I. G. Percival (eds) The Great Ordovician Biodiversification Event pp. 41–47. Columbia University Press.

Zhang, Y.-D., & A. C. Lenz. 1997. Uppermost Wenlock and Ludlow graptolites from southern Yunnan, China. Canadian Journal of Earth Sciences 34: 1220–1238.

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