''Petroxestes'' is a shallow, elongate boring (a type of

trace fossil A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, ...

) originally found excavated in carbonate skeletons and

hardgrounds Carbonate hardgrounds are surfaces of synsedimentarily cemented carbonate layers that have been exposed on the seafloor (Wilson and Palmer, 1992). A hardground is essentially, then, a lithified seafloor. Ancient hardgrounds are found in limestone ...

of the Upper

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

of North America (Wilson and Palmer, 1988, 2006). These Ordovician borings were likely made by the mytilacean

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

''Corallidomus'' as it ground a shallow groove in the substrate to maintain its feeding position (Pojeta and Palmer, 1976). They are thus the earliest known bivalve borings (Taylor and Wilson, 2003). ''Petroxestes'' was later described from the Lower

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

Anticosti Island ; moe, Notiskuan; mic, Natigostec , sobriquet = , image_name = RiviereHuileAnticosti.jpg , image_caption = Salmon fisherman on Rivière à l'Huile , image_map ...

(Canada) by Tapanila and Copper (2002) and the

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

of the

Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...

by Pickerill et al. (2001).

References

* * * * * * {{cite journal , author = Wilson, M.A., Palmer, T.J. , year = 2006 , title = Patterns and processes in the Ordovician Bioerosion Revolution , journal = Ichnos , volume = 13 , issue = 3 , pages = 109–112 , doi = 10.1080/10420940600850505, s2cid = 128831144 Boring fossils Paleozoic life of Quebec