First Evidence of the Cretaceous Decapod Crustacean Protocallianassa from Sweden
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Downloaded from http://sp.lyellcollection.org/ by guest on October 2, 2021 First evidence of the Cretaceous decapod crustacean Protocallianassa from Sweden ELISABETH EINARSSON1, ARON PRASZKIER1 & VIVI VAJDA1,2* 1Department of Geology, Lund University, So¨lvegatan 12, SE-223 62 Lund, Sweden 2Department of Palaeobiology, Swedish Museum of Natural History, PO Box 50007, SE-104 05 Stockholm, Sweden *Corresponding author (e-mail: [email protected]) Abstract: An assemblage of the burrowing ghost shrimp, Protocallianassa faujasi, is described, providing the first evidence of this decapod species from Sweden. The fossils occur in succes- sions of the informal earliest late Campanian Belemnellocamax balsvikensis zone at A˚ sen and the latest early Campanian B. mammillatus zone at Ivo¨ Klack, both in the Kristianstad Basin of NE Ska˚ne. Numerous, heavily calcified chelipeds were found within a restricted bed at A˚ sen that was rich in carbonate-cemented nodules. Based on the burrowing lifestyle of modern mud shrimps, we interpret these nodules as infilled burrow chambers. The low abundance of molluscs within the Protocallianassa beds is also consistent with analogous extant communities, indicating that a similar ecologically exclusive relationship ruled within the Late Cretaceous shallow- marine ecosystems. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. The Kristianstad Basin in the southernmost Swedish represented by sea-urchin spines (Erlstro¨m & Gabri- province of Ska˚ne hosts a richly fossiliferous suc- elson 1992; Surlyk & Sørensen 2010; Sørensen & cession of Upper Cretaceous marine deposits. The Surlyk 2011; Sørensen et al. 2013). The material Kristianstad Basin incorporates two half-graben for this study was recovered from the earliest late that are bordered by horsts to the SW; the entire Campanian succession at A˚ sen and the latest early faulted system occurs within a zone of tectonic Campanian succession at the Ivo¨ Klack locali- deformation known as the Tornqvist Zone (Erlstro¨m ties, and represents the first evidence of Protocalli- & Gabrielson 1992). During the mid-Late Creta- anassa, a burrowing shrimp, from Sweden. The ceous, repeated transgressive episodes occurred in morphology, stratigraphical provenance and envi- what today represents southern Scandinavia (Vajda ronmental context of the studied specimens are & Solakius 1999; Larsson et al. 2000). These cre- discussed. ated islands in the Kristianstad Basin that were surrounded by shallow seas forming paralic envi- ronments (Kominz et al. 2008; Surlyk & Sørensen Geological setting 2010) adjacent to the deeper Tethyan shelf to the SW. Today, these palaeoenvironments are repre- A˚ sen is situated a few kilometres north of the sented by several well-known fossil deposits, such small town of Bromo¨lla in the Kristianstad Basin as those exposed at Ignaberga, Ullstorp, Ivo¨ Klack (568 08′ 56.1′′ N, 148 29′ 56.0′′ E: Fig. 1). The site and A˚ sen (Fig. 1) (Bergstro¨m & Sundquist 1978; is currently a municipal landfill and recycling centre Erlstro¨m & Gabrielson 1992). The successions at (Einarsson et al. 2010; Sørensen et al. 2013). The A˚ sen and Ivo¨ Klack are especially rich in verte- strata at A˚ sen have been correlated with the mid- brate remains, including sharks, rays, actinoptery- Campanian informally termed Belemnellocamax gian fishes, mosasaurs, plesiosaurs, marine and mammilatus and Belemnellocamax balsvikensis bio- freshwater turtles, aquatic birds, and rare non-avian zones (Fig. 2) (Lindgren & Siverson 2002). These dinosaur bones (Einarsson et al. 2010; Sørensen equate to approximately 4 m of laterally thinning et al. 2013; Bazzi et al. 2015; Poropat et al. 2015; marine sediment (Fig. 2) resting upon upper San- Siversson et al. 2015). Coeval invertebrate assem- tonian and/or lower Campanian fluvio-lacustrine blages comprise bivalves, cephalopods, gastropods, argillaceous clays (Skarby 1968). The decapod brachiopods, bryozoans and echinoderms, mainly fossils occur in carbonate-cemented porous sand From:Kear, B. P., Lindgren, J., Hurum, J. H., Mila`n,J.&Vajda, V. (eds) Mesozoic Biotas of Scandinavia and its Arctic Territories. Geological Society, London, Special Publications, 434, http://doi.org/10.1144/SP434.6 # 2016 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ by guest on October 2, 2021 E. EINARSSON ET AL. Fig. 1. Schematic geological map of southern Sweden, Ska˚ne, with focus on the Kristianstad Basin. The studied localities A˚ sen and Ivo¨ Klack are marked on the map (modified after Siverson 1992). nodules set in unconsolidated quartz sand with abun- Systematic palaeontology dant glauconite. Ivo¨ Klack, historically called ‘Blaksudden’ Order Decapoda Latreille, 1802 (Christensen 1969), is a world-renowned fossil site Infraorder Axiidea de Saint Laurent, 1979 located at the northern point of Ivo¨ Island (568 08′ Family Callianassidae Dana, 1852 21.6′′ N, 148 24′ 05.8′′ E: Fig. 1). It is an abandoned Subfamily Protocallianassinae Beurlen, 1930 limestone and kaoline quarry that closed in the Genus Protocallianassa Beurlen, 1930 1950s. Stratigraphically basal kaolin clay that Protocallianassa faujasi Desmarest, 1822 formed during the early Mesozoic from weathering (Figs 4a–h & 5a–k) granites (Lidmar-Bergstro¨m et al. 2013) is overlain by quartz sands and a thin bed of dark clay, which Description. The decapod remains, all chelipeds was deposited under freshwater conditions (Chris- of moderate quality preservation, occur within tensen 1969). The overlying marine succession carbonate-cemented nodules that were collected comprises upper Campanian siliciclastic calcaren- from the earliest late Campanian, informal B. bals- ites (Surlyk & Christensen 1974). vikensis zone at A˚ sen between 2010 and 2012 (NRM-PZ Ar 63926–NRM-PZ Ar 63933). Isolated fossils were also found in slightly older strata (B. Methods mammillatus zone) at Ivo¨ Klack (NRM-PZ Ar 63934–NRM-PZ Ar 63944) by Richard Ha¨gg in Eighteen calcified chelipeds of Protocallianassa 1903. This assemblage also shows moderate pre- faujasi were measured based on their characters, servation. The recovered propodi all have intact illustrated in Figure 3, following the methods of fixed fingers, but the accompanying movable fin- Swen et al. (2001). The material is hosted at the ger is preserved in only a few specimens. The pro- Department of Palaeobiology, Swedish Museum of podi size is typical for Protocallianassa faujasi Natural History, Stockholm, Sweden. Institutional (Swen et al. 2001; Mourik et al. 2005). Other nota- abbreviations: NRM-PZ Ar 63926–NRM-PZ Ar ble features include a rectangular (longer than wide) 63944 (Table 1). manus, setal pits on the manus and fingers, in some Downloaded from http://sp.lyellcollection.org/ by guest on October 2, 2021 CRETACEOUS DECAPOD FROM SWEDEN Fig. 2. Stratigraphic section for the A˚ sen locality. Crustacean-bearing level within the B. balsvikensis zone is indicated. Note that sections further south along the quarry wall include a bed (up to 0.5 m thick) of B. mammillatus zone-age below the ‘Coquina bed’ (Siverson pers. comm.). Downloaded from http://sp.lyellcollection.org/ by guest on October 2, 2021 E. EINARSSON ET AL. carpus moveable finger manus (dactylus) iscium opposing margins basis fixed finger merus coxa propodus = manus + fixed finger Fig. 3. Anatomy of the decapod crustaceans cheliped with an example of a crab cheliped (modified after Collins 1999). specimens (probably abraded in others), and a manus width: 17, (14.6) and 10 based on 16 carpus–propodus angle exceeding 1008. specimens; fixed finger length: 11, (7) and 4 based on 12 Measurements. Pereiopod measurements (mm) specimens; were made according to Swen et al. (2001): maxi- carpus length: 21, (16.7) and 12 based on nine mum, (mean) and minimum dimensions are listed specimens; in Tables 1 and 2: angle manus/carpus: 1008, (1078) and 1158 based propodus length: 37, (28.5) and 23 based on 12 on 15 specimens. specimens; Remarks. Important taxonomic characteristics, such manus length: 28, (21) and 16 based on 16 as the propodus/manus ratio and the angle of the specimens; carpus–propodus joint, in the Kristianstad Basin Table 1. Cheliped measurements based on the specimens from the A˚ sen and Ivo¨ Klack localities included in this study Specimen Length of Length of Length of Width of Length of fixed Angle number carpus (mm) propodus (mm) manus (mm) manus (mm) finger (mm) (8) A˚ sen locality NRM-PZ Ar 63926 18.5 – 24 16 – 108 NRM-PZ Ar 63927 – 30 – – 10 – NRM-PZ Ar 63928 17 31 21 17 11 100 NRM-PZ Ar 63929 12 24.5 16 10 8 113 NRM-PZ Ar 63930 – – – 15 – – NRM-PZ Ar 63931 – 24 16 15 8 – NRM-PZ Ar 63932 21 – 20 14 – 102 NRM-PZ Ar 63933 – – – – – – Ivo¨ Klack NRM-PZ Ar 63934 15 23 18 14 5 105 NRM-PZ Ar 63935 17 – 21 15 – 100 NRM-PZ Ar 63936 16 – 20 – – 110 NRM-PZ Ar 63937 16 – 21 15 – 106 NRM-PZ Ar 63938 – 33 24 14 6 112 NRM-PZ Ar 63939 18 27 21 15 6 115 NRM-PZ Ar 63940 – 30 22 14 8 100 NRM-PZ Ar 63941 – 33 24 17 8 110 NRM-PZ Ar 63942 – 27 21 14 6 100 NRM-PZ Ar 63943 – 23 19 12 4 115 NRM-PZ Ar 63944 – 37 28 17 9 112 Mean values 16.7 28.5 21.0 14.6 7.0 107 Downloaded from http://sp.lyellcollection.org/ by guest on October 2, 2021 CRETACEOUS DECAPOD FROM SWEDEN Fig. 4. Chelipeds of Protocallianassa faujasi from the A˚ sen locality, Kristianstad Basin, southern Sweden: (a) manus with fragmented dactylus, and carpus; merus barely visible, NRM-PZ Ar 63932; (b) propodus with setal pits, NRM-PZ Ar 63927; (c)&(d) propodus and carpus, NRM-PZ Ar 63928 and NRM-PZ Ar 63929; (e) distal part of manus with part of dactylus and fixed finger, NRM-PZ Ar 63930; (f) distal part of manus with part of dactylus, NRM-PZ Ar 63933.