Editing Graptolite (section)

== Taxonomy ==
{{Further|List of graptolite genera}}
Since the 1970s, as a result of advances in [[electron microscopy]], graptolites have generally been thought to be most closely allied to the [[pterobranch]]s, a rare group of modern marine animals belonging to the phylum [[Hemichordata]].<ref name=Fortey>{{cite book |author=Fortey, Richard A. |author-link = Richard Fortey|title= Life: A Natural History of the First Four Billion Years of Life on Earth |publisher=Alfred A. Knopf |location=New York |year=1998 |page= 129 |title-link = Life: A Natural History of the First Four Billion Years of Life on Earth}}</ref> Comparisons are drawn with the modern hemichordates ''[[Cephalodiscus]]'' and ''[[Rhabdopleura]]''. According to recent phylogenetic studies, rhabdopleurids are placed within the Graptolithina. Nonetheless, they are considered an ''[[incertae sedis]]'' family.<ref name="Maletzclass" />

On the other hand, [[Cephalodiscida]] is considered to be a sister subclass of Graptolithina. One of the main differences between these two groups is that Cephalodiscida species are not colonial organisms. In Cephalodiscida organisms, there is no common canal connecting all zooids. Cephalodiscida zooids have several arms, while Graptolithina zooids have only one pair of arms. Other differences include the type of early development, the gonads, the presence or absence of [[gill slits]], and the size of the zooids. In the fossil record, where mostly tubaria (tubes) are preserved, it is complicated to distinguish between groups.

{{cladogram|title= Phylogeny of Pterobranchia<ref name= Maletzclass />|
{{clade
|label1='''Graptolithina'''|style=font-size:90%; line-height:90%; width:300px;
|1={{clade
  |1=[[Rhabdopleurida]]
  |label2=[[Eugraptolithina]]
  |2={{clade
    |1=[[Dendroidea]]
    |2=[[Graptoloidea]]
     }}
   }}
}}
}}

Graptolithina includes several minor families as well as two main extinct orders, '''Dendroidea''' ([[benthic]] graptolites) and '''Graptoloidea''' ([[planktic]] graptolites). The latter is the most diverse, including 5 suborders, where the most assorted is '''Axonophora''' (biserial graptolites, etc.). This group includes '''Diplograptids''' and '''Neograptids''', groups that had great development during the Ordovician.<ref name="Maletzclass" /> Old taxonomic classifications consider the orders Dendroidea, Tuboidea, Camaroidea, Crustoidea, Stolonoidea, Graptoloidea, and Dithecoidea but new classifications embedded them into Graptoloidea at different taxonomic levels.

Taxonomy of Graptolithina by Maletz (2014):<ref name= Maletzclass/><ref name="Maletzgp" />

Subclass '''Graptolithina''' <small>Bronn, 1849</small>
*''[[Incertae sedis]]''
**Family [[Rhabdopleuridae]] <small>Harmer, 1905</small>
**Family †[[Cysticamaridae]] <small>Bulman, 1955</small>
**Family †[[Wimanicrustidae]] <small>Bulman, 1970</small>
**Family †[[Dithecodendridae]] <small>Obut, 1964</small>
**Family †[[Cyclograptidae]] <small>Bulman, 1938</small>
*Order †Dendroidea <small>Nicholson, 1872</small>
**Family †[[Dendrograptidae]] <small>Roemer, 1897 in Frech, 1897</small>
**Family †[[Acanthograptidae]] <small>Bulman, 1938</small>
**Family †[[Mastigograptidae]] <small>Bates & Urbanek, 2002</small>
*Order †Graptoloidea <small>Lapworth, 1875 in Hopkinson & Lapworth, 1875</small> (planktic graptolites)
**Suborder †[[Graptodendroidina]] <small>Mu & Lin, 1981 in Lin (1981)</small>
***Family †[[Anisograptidae]] <small>Bulman, 1950</small>
**Suborder †[[Sinograpta]] <small>Maletz ''et al.'', 2009</small>
***Family †[[Sigmagraptidae]] <small>Cooper & Fortey, 1982</small>
***Family †[[Sinograptidae]] <small>Mu, 1957</small>
***Family †[[Abrograptidae]] <small>Mu, 1958</small>
**Suborder †[[Dichograptina]] <small>Lapworth, 1873</small>
***Family †[[Dichograptidae]] <small>Lapworth, 1873</small>
***Family †[[Didymograptidae]] <small>Mu, 1950</small>
***Family †[[Pterograptidae]] <small>Mu, 1950</small>
***Family †[[Tetragraptidae]] <small>Frech, 1897</small>
**Suborder †[[Glossograptina]] <small>Jaanusson, 1960</small>
***Family †[[Isograptidae]] <small>Harris, 1933</small>
***Family †[[Glossograptidae]] <small>Lapworth, 1873</small>
**Suborder †[[Axonophora]] <small>Frech, 1897</small> (biserial graptolites, and also retiolitids and monograptids)
***Infraorder †[[Diplograptina]] <small>Lapworth, 1880</small>
****Family †[[Diplograptidae]] <small>Lapworth, 1873</small>
*****Subfamily †[[Diplograptinae]] <small>Lapworth, 1873</small>
*****Subfamily †[[Orthograptinae]] <small>Mitchell, 1987</small>
****Family †[[Lasiograptidae]] <small>Lapworth, 1880e</small>
****Family †[[Climacograptidae]] <small>Frech, 1897</small>
****Family †[[Dicranograptidae]] <small>Lapworth, 1873</small>
*****Subfamily †[[Dicranograptinae]] <small>Lapworth, 1873</small>
*****Subfamily †[[Nemagraptinae]] <small>Lapworth, 1873</small>
***Infraorder †[[Neograptina]] <small>Štorch ''et al.'', 2011</small>
****Family †[[Normalograptidae]] <small>Štorch & Serpagli, 1993</small>
****Family †[[Neodiplograptidae]] <small>Melchin ''et al.'', 2011</small>
*****Subfamily †[[Neodiplograptinae]] <small>Melchin ''et al.'', 2011</small>
*****Subfamily †[[Petalolithinae]] <small>Bulman, 1955</small>
****Superfamily †[[Retiolitoidea]] <small>Lapworth, 1873</small>
*****Family †[[Retiolitidae]] <small>Lapworth, 1873</small>
******Subfamily †[[Retiolitinae]] <small>Lapworth, 1873</small>
******Subfamily †[[Plectograptinae]] <small>Bouček & Münch, 1952</small>
****Superfamily †[[Monograptoidea]] <small>Lapworth, 1873</small>
*****Family †[[Dimorphograptidae]] <small>Elles & Wood, 1908</small>
*****Family †[[Monograptidae]] <small>Lapworth, 1873</small>