Pterotheca attenuata: Difference between revisions
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==Preservation and Morphology== |
==Preservation and Morphology== |
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[[File:Pterotheca attenuata painting.jpg|thumb|left|Pterotheca attenuata |
[[File:Pterotheca attenuata painting.jpg|thumb|left|Pterotheca attenuata life restoration]] |
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The shell is composed of two slightly concave sub-triangular layers that connect along the anterior most side. The dorsal layer has a ridge that extends perpendicularly from the rest of shell right along the median plane. The underside of the ventral most layer is effaced and smooth, but the top of the ventral layer and the bottom of the dorsal layer both show a slight medial ridge. <ref>{{cite book |last1=Ulrich |last2=Scofield |last3=Clarke |last4=Winchell |title=The Geology of Minnesota |date=1895 |publisher=Geological and Natural History Survey of Minnesota |location=Minneapolis |edition=3}}</ref> |
The shell is composed of two slightly concave sub-triangular layers that connect along the anterior most side. The dorsal layer has a ridge that extends perpendicularly from the rest of shell right along the median plane. The underside of the ventral most layer is effaced and smooth, but the top of the ventral layer and the bottom of the dorsal layer both show a slight medial ridge. <ref>{{cite book |last1=Ulrich |last2=Scofield |last3=Clarke |last4=Winchell |title=The Geology of Minnesota |date=1895 |publisher=Geological and Natural History Survey of Minnesota |location=Minneapolis |edition=3}}</ref> |
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Revision as of 01:54, 22 March 2020
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| Pterotheca attenuata Temporal range: Early Ordovician – Late Ordovician,
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| Pterotheca attenuata from the Milwaukee Public Museum | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Subphylum: | Conchifera |
| Class: | Monoplacophora Odhner, 1940 |
| Binomial name | |
| Pterotheca attenuata (Ulrich, 1895)
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Pterotheca attenuata is a fossil from the Ordovician of upper Midwestern United States. It has been various classified as a member of monoplacophora, bellerophontida, or some other Gastropod group [1] [2]It lived in shallow marine waters and is a part of the Decorah Shale and Platteville Limestone fossil communities. It is often misclassified in museum collections because of its unusual morphology and therefore documentation of its range and abundance is poor.
Preservation and Morphology
The shell is composed of two slightly concave sub-triangular layers that connect along the anterior most side. The dorsal layer has a ridge that extends perpendicularly from the rest of shell right along the median plane. The underside of the ventral most layer is effaced and smooth, but the top of the ventral layer and the bottom of the dorsal layer both show a slight medial ridge. [3]
P. attenuata is most often preserved in fine grained sedimentary rock like shale and limestone, but its range likely extends outside of these facies. The shell is often found broken and the two layers separated. P. attenuata's unusual shape and the fragmentary nature of many of its fossils are both causes of its frequent misclassification.
References
- ^ "Pterotheca Salter 1853 (snail)". Fossil Works. The Paleobiology Database. Retrieved 20 March 2020.
- ^ Ulrich; Scofield; Clarke; Winchell (1895). The Geology of Minnesota (3 ed.). Minneapolis: Geological and Natural History Survey of Minnesota.
- ^ Ulrich; Scofield; Clarke; Winchell (1895). The Geology of Minnesota (3 ed.). Minneapolis: Geological and Natural History Survey of Minnesota.