Topic
Shimanskya
About: Shimanskya is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 32 citations.
Papers
1 Jan 2010
TL;DR: The morphological traits of the Carboniferous coleoids were analyzed to discover re-occurring combinations of different characteristic features during the early evolution of coleoid cephalopods.
Abstract: The morphological traits of the Carboniferous coleoids were analyzed to discover re-occurring combinations of different characteristic features during the early evolution of coleoid cephalopods. The early coleoid evolution in the Carboniferous is characterized by (1) a complex mosaic combination of the "old" and "new" morphological traits, (2) the parallel appearance and variations of new morphological features, and (3) relatively rapid changes in basic morphology. A mosaic combination is exemplified with Donovaniconus, which possesses a body chamber (bactritoid trait), a pro-ostracum-like structure (a novelty), and an ink sac (coleoid trait), or Mutveiconites, which combines a body chamber (bactritoid trait) and a rostrum (coleoid trait). A novelty or new feature can appear at any evolutionary stage, but "old" traits can continue to exist for a long period after the appearance of a novelty in another form. An example of this phenomenon is demonstrated by the evolutionary loss of the body chamber in the Lower Carboniferous (ca. 325 MY) taxon Hematites, which is the earliest recorded coleoid, and the retention of the body chamber in the Late Carboniferous (ca. 290 MY) taxa Shimanskya, Mutveiconites, Donovaniconus, and Saundersites. The parallel appearance of new morphological traits is illustrated by the appearance of the massive rostrum in the Early Carboniferous Hematites and the development of a cap-like small loosely calcified rostrum in the Late Carboniferous Mutveiconites.
23 citations
TL;DR: In this article, morphological features of the shell including internal structures of the phragmocones of three different bactritoid cephalopod taxa assigned to the Order Bactritida: Bactrites quadrilineatus, Ctenobactrites lesliensis (L. Carboniferous) and Rugobactrite jacksboroensis (U. carboniferous), were studied.
Abstract: Morphological features of the shell including internal structures of the phragmocones of three different bactritoid cephalopod taxa assigned to the Order Bactritida: Bactrites quadrilineatus, Ctenobactrites lesliensis (L. Carboniferous) and the Order Parabactritida: Rugobactrites jacksboroensis (U. Carboniferous) were studied. The material comes from South Central USA. The features examined include the conch shape, siphuncle shape and ultrastructure of the shell wall, septa, septal neck and the connecting ring. These traits were then compared with Shimanskya postremus from Upper Carboniferous of Texas, which has been originally referred to bactritids and later placed within the coleoids in the Order Spirulida. Based on similarities and differences observed, B. quadrilineatus and C. lesliensis are now also considered being coleoids similar to S. postremus; R. jacksboroensis remains placed in the Order Parabactritida.
16 citations
TL;DR: The Carboniferous genus Mitorthoceras from USA, previously assigned to orthocerids, is here restudied and assigned to the new coleoid order Tuborthocherida.
Abstract: The Carboniferous genus Mitorthoceras from USA, previously assigned to orthocerids, is here restudied and assigned to the new coleoid order Tuborthocerida. Mitorthoceras has several orthocerid char...
3 citations
Performance Metrics
| Year | Papers |
|---|---|
| 2019 | 1 |
| 2012 | 1 |
| 2010 | 1 |