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GEOREF RECORD

Coprolites in the Ravens Throat River Lagerstatte of northwestern Canada; implications for the Middle Cambrian food web

Julien Kimmig and Brian R. Pratt
Coprolites in the Ravens Throat River Lagerstatte of northwestern Canada; implications for the Middle Cambrian food web
Palaios (April 2018) 33 (4): 125-140

Abstract

The Rockslide Formation (middle Cambrian, Drumian, Bolaspidella Zone) of the Mackenzie Mountains, northwestern Canada, hosts the Ravens Throat River Lagerstatte, which consists of two, 1-m thick intervals of greenish, thinly laminated, locally burrowed, slightly calcareous mudstone yielding a low-diversity and low-abundance fauna of bivalved arthropods, 'worms', hyoliths, and trilobites. Also present are flattened, circular, black carbonaceous objects averaging 15 mm in diameter, interpreted as coprolites preserved in either dorsal or ventral view. Many consist of aggregates of ovate carbonaceous flakes 0.5-2 mm long, which are probably compacted fecal pellets. Two-thirds contain a variably disarticulated pair of arthropod valves, and many also contain coiled to fragmented, corrugated 'worm' cuticle, either alone or together with valves. A few contain an enrolled agnostoid. In rare cases a ptychoparioid cranidium, agnostoid shield, bradoriid valve, or hyolith conch or operculum is present; these are taken to be due to capture and ingestion of bioclasts from the adjacent seafloor. Many of the coprolites are associated with semi-circular spreiten produced by movement of the worm-like predator while it occupied a vertical burrow. Its identity is unknown but it clearly exhibited prey selectivity. Many coprolites contain one or more articulated hyoliths, ptychoparioid trilobites, or outstretched agnostoid arthropods oriented dorsal side up. These are interpreted as opportunistic coprovores drawn to the organic-rich fecal mass while it was lodged near the entrance to the burrow. This argues that hyoliths were mobile detritivores, and agnostoids were mainly nektobenthic or benthic, like the ptychoparioid trilobites. Fecal matter was probably an important source of nutrition in the Cambrian food web.


ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 33
Serial Issue: 4
Title: Coprolites in the Ravens Throat River Lagerstatte of northwestern Canada; implications for the Middle Cambrian food web
Affiliation: University of Kansas, Biodiversity Institute, Lawrence, KS, United States
Pages: 125-140
Published: 201804
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 65
Accession Number: 2018-037265
Categories: Invertebrate paleontology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. strat. col., 2 plates, sketch map
N63°15'00" - N63°15'00", W127°30'00" - W127°30'00"
Secondary Affiliation: University of Saskatchewan, CAN, Canada
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 201809
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