Petroxestes pera bivalve boring in a fossil bryozoan skeleton (Kope Formation, Upper Ordovician; Campbell County, Kentucky, USA) 4 : 無料・フリー素材/写真
Petroxestes pera bivalve boring in a fossil bryozoan skeleton (Kope Formation, Upper Ordovician; Campbell County, Kentucky, USA) 4 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Petroxestes pera Wilson & Palmer, 1988 - bivalve boring in a fossil bryozoan skeleton from the Ordovician of Kentucky, USA.The slit-shaped hole at the summit of this fossil bryozoan is a boring made by a clam. Borings are one of many categories of trace fossils - any indirect evidence of ancient life. Other examples include burrows, tracks, trails, footprints, and bitemarks. Trace fossils, also called ichnofossils, record the behavior of ancient organisms. Traces are given Latin scientific names in the same style as living organisms or body fossils.This Petroxestes boring was made by the bivalve Corallidomus scobina. Bivalves are bilaterally symmetrical molluscs having two calcareous, asymmetrical shells (valves) - they include the clams, oysters, and scallops. In most bivalves, the two shells are mirror images of each other (the major exception is the oysters). They occur in marine, estuarine, and freshwater environments. Bivalves are also known as pelecypods and lamellibranchiates.Bivalves are sessile, benthic organisms - they occur on or below substrates. Most of them are filter-feeders, using siphons to bring in water, filter the water for tiny particles of food, then expel the used water. The majority of bivalves are infaunal - they burrow into unlithified sediments. In hard substrate environments, some forms make borings, in which the bivalve lives. Some groups are hard substrate encrusters, using a mineral cement to attach to rocks, shells, or wood.The fossil record of bivalves is Cambrian to Recent. They are especially common in the post-Paleozoic fossil record.Petroxestes borings very rarely have a bivalve body fossil still occupying the slit. The type specimen of Petroxestes pera is a boring incised into a solid, calcareous, bryozoan colony, as is this specimen.The bryozoan itself is the trepostome Prasopora simulatrix Ulrich, 1886. Bryozoans are colonial lophophorates, most of which make a calcareous skeleton. Many bryozoan skeletons have complex shapes that cannot be fully appreciated from the fossil record. Bryozoans are abundant fossils, especially in Paleozoic and Mesozoic limestones, but their skeletons usually get busted up during the storm events resulting in their final burial.Classification of borer: Animalia, Mollusca, Bivalvia, Heteroconchia, Modiomorphida, ModiomorphidaeClassification of bryozoan: Animalia, Lophophorata, Bryozoa, Stenolaemata, Trepostomata, MonticuliporidaeStratigraphy: Kope Formation, Edenian Stage, lower Cincinnatian Series, Upper OrdovicianLocality: undisclosed site in Campbell County, northern Kentucky, USA-----------------------------------Info. at:stratigrafia.org/cincy/fauna/trepostomatida/Prasopora.html |
| 撮影日 | 2025-05-01 14:50:55 |
| 撮影者 | James St. John |
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