Ichnos An International Journal for Plant and Animal Traces ISSN: 1042-0940 (Print) 1563-5236 (Online) Journal homepage: https://www.tandfonline.com/loi/gich20 Cutting-edge technology: burrows lined with sponge bioclasts from the Upper Cretaceous of Denmark Lothar H. Vallon, Jesper Milàn, Andrew K. Rindsberg, Henrik Madsen & Jan Audun Rasmussen To cite this article: Lothar H. Vallon, Jesper Milàn, Andrew K. Rindsberg, Henrik Madsen & Jan Audun Rasmussen (2020): Cutting-edge technology: burrows lined with sponge bioclasts from the Upper Cretaceous of Denmark, Ichnos, DOI: 10.1080/10420940.2020.1744581 To link to this article: https://doi.org/10.1080/10420940.2020.1744581 Published online: 09 Apr 2020. Submit your article to this journal View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=gich20 ICHNOS https://doi.org/10.1080/10420940.2020.1744581 Cutting-edge technology: burrows lined with sponge bioclasts from the Upper Cretaceous of Denmark Lothar H. Vallona ,JesperMilana , Andrew K. Rindsbergb ,HenrikMadsenc and Jan Audun Rasmussenc aGeomuseum Faxe, Østsjællands Museum, Faxe, Denmark; bBiological & Environmental Sciences, University of West Alabama, Livingston, Alabama, USA; cFossil-og Molermuseet, Museum Mors, Nykøbing Mors, Denmark ABSTRACT KEYWORDS Many tracemakers use different materials to line their burrows. Koptichnus rasmussenae n. Domichnia; wall igen. n. isp. is lined with cuboid fragments of siliceous sponges, interpreted as evidence of construction; sediment harvesting and trimming material to reinforce the burrow wall. The act of trimming, as evi- consistency; Porifera; Stevns Klint; Arnager; Hillerslev; denced in the polyhedral faces, is considered to be behaviourally significant. The tracemaker Coniacian; Maastrichtian; was evidently a lobster-like crustacean. new ichnotaxa 1. Introduction lined with plant material (e.g., Upper Cretaceous of Georgia, USA; personal observation, AKR), modern Linings constructed of added material are part of burrows of lemmings and voles (Vallon and Kjeldahl- many domichnia and some fodinichnia (e.g., Frey and Seilacher 1980; Knaust 2012). They may consist of Vallon 2011), subhorizontal burrows lined with fish materials such as mucus, silk, sediment particles, plant scales (Lepidenteron Fritsch 1877; Suhr 1988; debris, bioclasts, or components shaped by the trace- Jurkowska and Uchman 2013), and vertical to subverti- maker itself, such as pellets. Linings are usually cal, thickly lined (perhaps in parts surficial) burrows applied to a burrow’s wall to prevent collapse of soft made of mollusc fragments (Diopatrichnus Kern € sediment, to optimise burrow irrigation by sealing off 1978), foraminifera (Nummipera Holder 1989), and permeability to the surrounding sediment (e.g., bryozoans (Baronichnus Breton 2002). The horizontal Sch€afer 1956; Aller 1983; Bromley 1996:18–19; Zorn, Ereipichnus Monaco et al. (2005) is also characterised Gingras, and Pemberton 2010), or even for insulation by a thick lining, usually built in several concentric (e.g., grass and moss linings in lemming burrows; layers of laminar bioclasts and other particles coarsen- Vallon and Kjeldahl-Vallon 2011). Many of these lin- ing outwards. Though probably endogenic, its dense ings allow microbial growth that may be exploited as or intertwined growth of several tubes suggests that a food source, marking transitions from domichnia or the lined part could have been surficial. fodinichnia to agrichnia (Vallon, Rindsberg, and In contrast to endogenic traces, surficial tubes built Bromley 2016). Especially in long-lasting structures, as chimneys or mobile homes commonly incorporate tracemakers expend much time, not only collecting bioclasts as protection and camouflage, for example, suitable materials, but also shaping and assembling ‘Terebella’ lapilloides Munster€ in Goldfuss, 1833 (sedi- them (Watson 1890; Fager 1964; Anderson and ment particles), Crininicaminus Ettensohn 1981 (cri- Meadows 1978; Bromley 1996). noidal skeletal parts), and several fossil caddisfly larval Bioclastic linings are uncommon compared to lin- cases named according to their dominant lining ings of mucus-bound sediment (e.g., pellets in material (Berry 1927; Vialov 1973; Vialov and Ophiomorpha); such lined burrows are termed ar- Sukatsheva 1976; Jarzembowski 1995). moured burrows by Buatois et al. (2017). Mendoza- In our case, the Cretaceous chalk deposits at Rodrıguez et al. (2019: fig. 4) summarised these Hillerslev (northern Jylland), Stevns Klint (Sjælland) mostly rare ichnotaxa. Armoured burrows can be di- and Arnager (Bornholm) originally consisted of ma- vided into endogenic (subsurficial) and exogenic (sur- rine softgrounds (Hansen and Surlyk 2014). The ficial) forms. Endogenic forms include Thalassinoides observed linings are composed of densely packed CONTACT Lothar H. Vallon [email protected] Geomuseum Faxe, Østsjællands Museum, Faxe, Denmark ß 2020 Informa UK Limited, trading as Taylor & Francis Group 2 L. H. VALLON ET AL. Figure 1. Location map within Denmark: 1 ¼ Hillerslev Quarry, 2 ¼ Sigerslev Quarry, 3 ¼ Arnager Cliff. bioclasts and therefore must have been constructed to (Damholt and Surlyk 2012) and trace fossils (Bromley prevent the burrows from collapsing during occupa- and Ekdale 1984; Ekdale and Bromley 1984). In this tion by the tracemakers; despite this, most specimens area, the mainly pelagic, coccolithic ooze was shaped collapsed, presumably after abandonment. Although into mounds below the photic zone by gentle bottom most other burrows from these sites lack linings currents (Surlyk, Damholt, and Bjerager 2006). These (Bromley and Ekdale 1984; Ekdale and Bromley currents provided nutrients, allowing bryozoans and 1991), the preserved fauna does show adaptations to other invertebrates (e.g., siliceous sponges) an initial softgrounds (e.g., Heinberg 2012; Hansen and Surlyk colonization of the mounds towards the end of the 2014). In an environment dominated by continual Maastrichtian (Anderskouv, Damholt, and Surlyk sedimentation, like the Danish Maastrichtian chalk 2007). The stratigraphic succession exposed at (e.g., Surlyk et al. 2013), this suggests that lined bur- Sigerslev Quarry is approximately 40 m thick. The rows originate from shallower seafloor tiers than the lower 30 m consists of mounded chalk rich in bryo- trace fossils that are usually preserved. zoan fragments and sponges. It is overlain by evenly bedded, benthos-poor but Zoophycos-rich chalk of the 2. Geological setting Sigerslev Member (Møns Klint Formation; Surlyk, Damholt, and Bjerager 2006, Surlyk et al. 2013; 2.1. Sigerslev Hansen and Surlyk 2014). The Sigerslev Member is The Sigerslev Quarry is located at Stevns Klint, in the capped by two closely spaced incipient hardgrounds. eastern part of Sjælland (Figure 1), where a complete In the uppermost Maastrichtian Højerup Member, succession through the Cretaceous–Palaeogene bound- mounded bryozoan-rich chalk reappeared, only a few ary (upper Maastrichtian chalk of the Møns Klint meters thick (Surlyk, Damholt, and Bjerager 2006, Formation to lower Danian bryozoan limestone of the Surlyk et al. 2013). Trace fossils, mainly Zoophycos Stevns Klint Formation) is exposed, yielding an exten- and Thalassinoides, are common throughout the for- sive fossil record of 450 species of invertebrates mation (Bromley and Ekdale 1984; Ekdale and ICHNOS 3 Bromley 1984) and extensive paramoudras can be 3. Systematic ichnology observed in the quarry walls. 3.1. Koptichnus n. igen. Diagnosis: Burrow with subcircular cross-section, 2.2. Hillerslev mainly parallel to bedding plane, occasionally The Hillerslev quarry situated north of Thisted in branched with Y-shaped junctions, with thick lining northwestern Jylland (Figure 1) is located in the of bioclasts of uniform size and shape; fill passive. Danish Basin immediately south of the Tornquist Derivatio nominis: Ancient Greek κόpsx, cut, fell, Zone. It exposes chalk from the upper Maastrichtian slay; and latinised Greek ichnus, trace. tenuicostata–semiglobularis and/or semiglobularis– Remarks: Two other ichnogenera are somewhat humboldtii brachiopod zones of the Møns Klint similar to Koptichnus.Thefirst,Lapillitubus Formation (Surlyk 1984; Surlyk et al. 2013). Belaustegui and Belaustegui (2017), is an unbranched Ammonites are relatively common at Hillerslev, burrow with a lining composed of lithoclasts (never including various (sub)species of Hoploscaphites bioclasts) of variable size and therefore only has a together with Saghalinites wrighti and Pachydiscus superficial resemblence to Koptichnus. The second is neubergicus (Birkelund 1993; Machalski 2005). Ichnospongiella Rigby, Xichun, and Jiasong (1998) Siliceous sponges also are abundant, especially in two which has a lining of sponge spicules bound with a areas, which possibly indicates the occurrence of small dense matrix. These spicules are isolated, variable in patch reefs. Systematic trace-fossil description has not size and neither oriented nor bundled. The burrows been undertaken. In the sediment a few undetermined are branched but thin-walled. burrows filled with dark, structureless material The strong uniformity in size and geometric shape are present. of the lining material of Koptichnus n. igen. suggests that the tracemaker actively shaped it. We refer to no particular building material in the ichnogeneric dia- 2.3. Arnager gnosis because we consider the evidence of trimming At the coastal cliff