Examine individual changes

'@@ -20,5 +20,5 @@ }} -'''Pterotheca attenuata''' is a fossil from the Ordovician [[Upper Midwest|upper Midwestern United States]]. It has been variously classified as a [[monoplacophora|monoplacophoran]], [[bellerophontida|bellerophont]], or some other [[Gastropoda|gastropod]].<ref>{{cite web |title=Pterotheca Salter 1853 (snail) |url=http://fossilworks.org/?a=taxonInfo&taxon_no=8368 |website=Fossil Works |publisher=The Paleobiology Database |accessdate=20 March 2020 |ref=Fossilworks}}</ref><ref name=":0">{{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> 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. +'''Pterotheca attenuata''' is a fossil from the Ordovician [[Upper Midwest|upper Midwestern United States]]. It has been variously classified as a [[monoplacophora|monoplacophoran]], [[bellerophontida|bellerophont]], or some other [[Gastropoda|gastropod]].<ref>{{cite web |title=Pterotheca Salter 1853 (snail) |url=http://fossilworks.org/?a=taxonInfo&taxon_no=8368 |website=Fossil Works |publisher=The Paleobiology Database |accessdate=20 March 2020 |ref=Fossilworks}}</ref><ref name=":0">{{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> 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.<ref name=":1">{{cite web |last1=Tweet |first1=Justin |title=Decorah gastropods (and some things that look like gastropods) |url=https://equatorialminnesota.blogspot.com/2018/11/decorah-gastropods.html |website=Equatorial Minnesota |accessdate=24 March 2020}}</ref> ==Preservation and morphology== @@ -26,5 +26,5 @@ 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 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 name=":0" /> -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. +P. attenuata is most often preserved in fine grained sedimentary rock like shale and limestone, but its range likely extends outside of these [[facies]]. <ref>{{cite journal |last1=Sloan |first1=Robert |title=RI-35 Middle and Late Ordovician Lithostratigraphy and Biostratigraphy of the Upper Mississippi Valley |journal=Minnesota Geological Survey |date=1987 |url=https://conservancy.umn.edu/handle/11299/60756 |accessdate=24 March 2020}}</ref> 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 as a [[brachiopoda|brachiopod]].<ref name=":1" /> == References == '