Chemical processing of fossil phyllocarid cuticle: A comparison of micro- and macrofossil remains

ABSTRACTCuticular remains of the phyllocarid crustaceans Caryocaris? and Ceratiocaris? obtained via maceration of macrofossil remains in hydrofluoric acid are compared with dispersed fragments isolated using both the low-manipulation HF extraction and the standard HCl–HF–HCl method. The studied specimens were obtained from Ordovician and Silurian shales of the Šárka and Požáry formations (Prague Basin, Barrandian area, Czech Republic). This methodological approach allows a direct comparison of macrofossil remains with microfossils in residue. The differences in residues obtained through the two bulk-rock extraction methods are also discussed.KEYWORDS: phosphatic microfossilsorganic-walled microfossilsextraction methodsearly PaleozoicPrague BasinDisclaimerAs a service to authors and researchers we are providing this version of an accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proofs will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to these versions also. AcknowledgmentsThe authors would like to thank Ondřej Zicha (Prague) for providing specimens of Caryocaris and Saltericaris for the in situ study. We would further like to thank Monika Uhlířová and Zuzana Strossová (both Charles University Prague) for aid with collecting samples at Kosov quarry, Lena Kraus (Senckenberg Gesellschaft für Naturforschung) for assistance during laboratory processing of bulk rock samples from the Šárka Formation and Jana Čepičková (Charles University Prague) for providing literature, Lucy Muir for language editing, and finally to Vera Korasidis, Ben Slater and an anonymous referee for providing valuable feedback that significantly improved the manuscript.Disclosure statementNo potential conflict of interest was reported by the authors.FundingVK acknowledges support by the project “Grant Schemes at CU “(reg. no. CZ.02.2.69/0.0/0.0/19_073/0016935). OF acknowledges support by Cooperatio GEOL of the Ministry of Education, Youth and Sports of the Czech Republic.Figure 1 (A) Distribution of lower Paleozoic rocks within the Prague Basin and its location within the Czech Republic. (B) Stratigraphical subdivision of the Ordovician and Silurian of the Prague Basin with highlighted Šárka and Požáry formations (sampled in this study).Display full sizeFigure 2 Remains of Caryocaris? on a bedding plane (Ba, Ca, Da) and from microfossil residues (A, Bb, Cb, Db) placed upon a reconstruction. Scale bars represent 100 µm for all specimens except Cb. In Cb, the scale bar represents 50 µm.Display full sizePlate 1. Cuticular fragments of Caryocaris? sp. extracted (a) directly from macrofossil (2,7), (b) via ‘low-manipulation HF extraction’ process (4–6, 8–11, 13–18), (c) via HCl-HF-HCl processing (3) and a coniform conodont (12) from the locality Praha - Na Salátce quarry (Šárka Formation, Darriwilian, Middle Ordovician). Scale bars represent: 50 µm (1, 3, 4, 6, 8–10, 12, 14–16, 18); 200 µm (2); 100 µm (5, 7, 11, 17); 20 µm (13). Specimens 2, 7 were extracted directly from macrofossil, 1,4–6, 8–18 were extracted via the ‘low-manipulation HF extraction’ method, and specimen 3 was isolated using a standard palynological processing method.1. Slide ŠS–JEN–29b, EF: W42(3)2. Slide ŠS–JEN–Caryocaris_a, EF: V51(1)3. Slide ŠS–JEN–30a, EF: E394. Slide ŠS–JEN–29b, EF: E36(2)5. Slide ŠS–JEN–29b, EF: P30(4)6. Slide ŠS–JEN–29b, EF: Q64(4)7. Slide ŠS–JEN–Caryocaris_a, EF: R458. Slide ŠS–JEN–29b, EF: E54(3)9. Slide ŠS–JEN–29c, EF: B6410. Slide ŠS–JEN–29b, EF: O59(3)11. Slide ŠS–JEN–29b, EF: C53(4)12. Slide ŠS–JEN–29b, EF: H46(3)13.-18. Stub SAF_1Display full sizePlate 2. Remains of Ceratiocaris? sp. (1–3, 6, 7), unknown arthropod (9), and conodonts (4, 5) from the Kosov quarry (Požáry Formation, Přídolí, late Silurian). Scale bar represents: 400 µm (1,2), 100 µm (3), 50 µm (4–7). Specimens 1–3 were extracted directly from macrofossil, 4,5,8,9 extracted via the ‘low-manipulation HF extraction’ process and 6,7 using a standard palynological processing method.1. Slide PS-K-FY-1, EF: W48(3)2. Slide PS-K-FY-1, EF: K44(1)3. Slide PS-K-FY-1, EF: W47(1)4. Slide PS-K-L-6c, EF: G29(4)5. Slide PS-K-L-6b, EF: G38(3)6. Slide PS-K-8c, EF: K43(3)7. Slide PS-K-8c, EF: G39(2)8. Slide PS-K-L-2, EF: F38(4)9. Slide PS-K-L-4c, EF: N37(2)Display full size