Pterocyrtidium

Daughter taxa (time control age-window is: 0-800Ma)
				Pterocyrtidium barbadense neptune records: 45
				Pterocyrtidium borisenkoi neptune records:
				Pterocyrtidium genriettae neptune records: 14
				Pterocyrtidium praebarbadense neptune records:
				Pterocyrtidium sp. neptune records: 1

Taxonomy

Catalog entries: Pterocyrtidium

Original description: Pterocyrtidium mh. (Pterocanium E. p. p.). Große Schwierigkeiten hereitet die Ableitung dieser Gruppe. Die hierher gehörigen Formen schließen sich ihrer allgemeinen Bauweise nach sehr innig an die dreigliedrigen eigentlichen Eucyrtidien an (Fig. 28 und 29), zeichnen sich jedoch dadurch aus, dass vom ersten Glied drei oder auch zwei mäßig lange Stacheln entspringen, welche ihrer Lage nach den Primärstacheln entsprechen. Die Schwierigkeit der Herleitung liegt darin, dass wir bei der zweigliedrigen Lithomelissa diese drei Stacheln des ersten Gliedes als einen sehr primitiven Charakter kennen gelernt haben, so dass die Ableitung unserer Formen von Lithomelissa gleichfalls möglich erscheint. Es ließe sich vielleicht für die hier gewählte Herleitung von Eucyrtidium geltend machen, dass die Litliomelissastacheln sich ins Innere der Höhlung des ersten Gliedes bis zu den Basallöchern verfolgen lassen, was hier nicht der Fall zu sein scheint. Wenn wir die hier gewählte Ableitung beibehalten, so müssen wir uns vorstellen, dass die drei Stacheln von Pterocyrtidium nicht den eigentlichen drei primären Mündungsstacheln entsprechen, die nach unserer Auffassung ja in den Wandungen selbst verlaufen, sondern Stachelbildungen sekundärer Natur sind, welche sich von den in der Wand laufenden Stacheln nach außen abzweigen. Ich habe zwei hierher gehörige Formen untersucht, von welchen mir die eine neu scheint (Fig. 28 a-b), ich nenne sie Pterocyrtidium Zitteli n. f., die zweite ist Pterocanium barbadense Ehbg. Bei beiden ist der zygocyrtide Bau des Köpfchens deutlich ausgeprägt. Fig. 28 a zeigt, dass der Primärring sehr wohl erhalten ist. Hierher gehören weiterhin noch: Pterocanium Sabae E. (Eucyrtidium ?carinatum H., damit wahrscheinlich identisch), Pteroc. Apis E., ? Pterocanium falciferum St. und ? Pteroc. bibrachiatum St. Zu dieser Gruppe dürfte weiterhin zu ziehen sein: Dictyoceras Virchowii Hck., da die Porosität der Stacheln nur ein sekundärer Character ist.


Translated description: Pterocyrtidium (n.gen). (Pterocanium Ehr. pro partim). The definition of this group is rather difficult. The species examined here can easily be related to the true Eucyrtidiids having 3 segments (figs. 28, 29) by their general structure, but they are distinguished in having a first segment with three or two medium-sized horns related to the internal spines. The problem is that we have attributed a primitive character to the same structure of the three external horns in the two-segmented Lithomelissa, so that these forms could originate from Lithomelissa. In this case, grouping Pterocyrtidium within the Eucyrtidiids (as it is done here) would infer that the three horns of Lithomelissa are extending inside to the collar plate, which is not true. If we consider that the Eucyrtidiid grouping is right, we can, thus, think that the three horns of Pterocyrtidium do not correspond to the three primary spines of the opening that, in our opinion, are developped in the shell wall, but that they are secondary structured issued from the spines growing inside the wall and diverging outside. Until now, I have examined two forms of this kind, one seeming new (fig. 28a-b) that I have named Pterocyrtidium zitteli, n. sp., the second one being Pterocyrtidium barbadense Ehrenberg. These two forms have a cephalis of well-marked zygocyrtid structure. Figure 28a shows a well-preserved primary ring. These two species will probably form a group with Pterocanium sabae (= probably Eucyrtidium ? carinatum Hck.), Pterocanium apis Ehrenberg, ?Pterocanium falciferum Stöhr, and ? Pterocanium bibrachiatum Stöhr. To this group should be added Dictyoceras virchowii with a porous shell that can only be considered as a secondary characteristic. Translation by J.P.C.]]
Remarks on original description: [Campbell [1954, p.D87] designates Pterocorys campanula Haeckel, 1887a as the type species of Pterocyrtidium. However, this seems inappropriate as this species was not among those included at the time of the genric definition. Species included at that time are: Lithornithium dictyoceras Haeckel,1860b; Pterodon apis Ehrenberg, 1873a; Pterocytidium zitteli Butschli, 1882b; Pterocanium barbadense Ehrenberg, 1873; P.sabae Ehrenberg, 1872a.]

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of Paleogene Period (100% up, 23Ma, in Aquitanian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within Paleogene Period (23.03-66.04Ma, base in Danian stage). Data source: Total of ranges of species in this database

Plot of occurrence data:

• Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
• Triangles indicate an event for which a precise placement has been suggested
• Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Lophocyrtiidae

Pterocyrtidium compiled by the radiolaria@mikrotax project team viewed: 19-9-2024 Taxon Search: Advanced Search Short stable page link: https://mikrotax.org/radiolaria/index.php?id=205248 Go to Archive.is to create a permanent copy of this page - citation notes

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