Radek Mikuláš

Three New Ichnogenera of Biting and Gnawing Traces on Reptilian and Mammalian Bones: A Case Study from the Miocene of the Czech Republic

The Ahníkov (Miocene, Czech Republic) site represents a concentration of vertebrate skeletal remains in a swamp setting. Autochthonous bone deposits were strongly altered by sedimentary processes and early diagenesis. Biting and gnawing traces recognized on hard animal tissues (bones, teeth, antlers, turtle thoraces) represent seven recurring morphotypes. The following ichnotaxa are erected: Nihilichnus nihilicus n. igen. et n. isp., Nihilichnus mortalis n. isp., Machichnus regularis n. igen. et n. isp., Machichnus multilineatus n. isp., Machichnus bohemicus n. isp., and Brutalichnus brutalis n. igen. et n. isp. Each kind of bones or similar substrates bears a specific proportion of various bite traces but no observed morphotype is specific for a single substrate. Ethologically, traces of sharpening of teeth are principally different from predation traces. The beavers Steneofiber eseri and Steneofiber depereti, the carnivore Amphicyon sp. and the crocodiles are presumed as the tracemakers.

Traces within traces: holes, pits and galleries in walls and filling of insect trace fossils in paleosols

Fossil insect nests with constructed walls (ichnogenera Uruguay ROSELLI 1938, Palmiraichnus ROSELLI 1987, Rosellichnus GENISE and BOWN 1996), as well as fossil brood masses from dung beetles (Monesichnus ROSELLI 1987) often display pits or galleries made by inquilines, parasitoids, cleptoparasites and scavengers, which develop and/or feed inside them. Some of these “traces within traces” can be distinguished, using morphologic criteria, as separate ichnotaxa. Tombownichnus n. igen. is represented by circular to subcircular holes or paraboloid external pits occurring in discrete walls of chambers made of agglutinated soil material. T. plenus n. isp. consists of a complete perforation, mostly cylindrical in longitudinal section, which pierces whole thickness of the cell wall. Tombownichnus parabolicus n. isp. includes incomplete perforations, i.e. pits, parabolic, conic or subcylindrical in longitudinal section, on the external surface of the chamber wall. Lazaichnus fistulosus n. igen., n. isp. is composed of circular to subcircular holes occurring in constructed walls of chambers made of agglutinated soil material, which are connected to an internal gallery in their infillings. The trace fossils described herein may be the first formal records of this hitherto neglected but promising field of ichnologic research.

The ichnogenus Curvolithus revisited

The ichnogenus Curvolithus Fritsch, 1908, originally described from the Ordovician of the Prague Basin, typically comprises ribbonlike or tonguelike, flattened, endostratal traces with three rounded lobes on the upper surface. However, considerable confusion persists regarding the ichnotaxonomic status and diagnostic features of its ichnospecies. The type specimens of this ichnotaxon, overlooked in most subsequent reports, are redescribed herein. Curvolithus multiplex Fritsch, 1908, the type species, is retained for specimens with a trilobate upper surface and a quadralobate lower surface, in contrast to the criteria adopted by subsequent authors. The other ichnospecies originally proposed from the type locality, C. gregarius Fritsch, 1908, actually consists of a series of grouped parallel scratch marks forming ridges and should be removed from Curvolithus. Subsequently, four ichnospecies were defined: C.? davidis Webby 1970; C. annulatus Badve and Ghare 1978; C. aequus Walter et al. 1989; and C. manitouensis Maples and Suttner 1990. Curvolithus? davidis shows the typical trilobation of Curvolithus apparently in its lower surface, but the morphology of the upper surface is uncertain. Accordingly, it does not warrant ichnospecific assessment, and is regarded as a nomen dubium. The nature of the annulations on the trilobate upper surface of C. annulatus is unclear, and this ichnospecies is also best considered as a nomen dubium. Curvolithus aequus has a bilobate lower surface and probably represents washed out specimens of Didymaulichnus. Finally, C. manitouensis comprises specimens with a smooth, trilobate upper surface and a smooth, quadralobate lower surface, and is best regarded as a junior synonym of C. multiplex. Curvolithus multiplex has been used incorrectly for Curvolithus with a trilobate upper surface and a trilobate to unilobate lower surface. The new ichnospecies, Curvolithus simplex, is proposed herein for such traces. Curvolithus is interpreted as a locomotion trace (Repichnia) of endostratal carnivores, possibly gastropods, flatworms, or nemerteans. Curvolithus is a component of the Cruziana ichnofacies in shallow-marine facies, either of normal salinity or slightly brackish, in the latter case typically associated with fan deltas.

Paleoecologic Implications of Ichnofossils Associated with Slightly Skeletonized Body Fossils, Middle Cambrian of the Barrandian Area, Czech Republic

Several sites of the Middle Cambrian Jince and Buchava formations (Barrandian area, Czech Republic), showing features of Burgess Shale-type preservation, yielded diverse ichnofossils adjacent to non- or poorly biomineralized body fossils of arthropods, and less commonly, acrotretid brachiopods. Based on morphology, Gordia-like, Cochlichnus-like, Planolites-like, Treptichnus-like and Pilichnus-like traces occur with “nondescript” bioturbation. Ethologically, the Gordia-like and Cochlichnus-like traces are interpreted as single-use traces of feeding on microbial halo. Treptichnus-like and Pilichnus-like traces suggest later feeding systems associated also with feeding on microbial halo, and Planolites-like traces likely represent a fortuitous feature.

A History of Ideas in Ichnology

Abstract Although the concept of ichnology as a single coherent field arose in the nineteenth century, the endeavor of understanding traces is old as civilization and involved cultural areas worldwide. In fact, fossil and recent traces were recognized since prehistoric times and their study emerged from the European Renaissance. This progression, from empirical knowledge toward the modern concepts of ichnology, formed a major research field which developed on a global scale. This report outlines the history of ichnology by (1) exploring the individual cultural areas, (2) tracing a comprehensive bibliographic database, and (3) analyzing the evolution of ichnology semiquantitatively and in a graphical form (“tree of ichnology”). The results form a review and synthesis of the history of ichnology, establishing the individual and integrated importance of the different ichnological schools in the world.

Ichnologic note: The ophiuroid Taeniaster as a tracemaker of Asteriacites, ordovician of czechoslovakia

The brittle star Taeniaster bohemicus was found in association with the trace fossil Asteriacites lumbricalis in the Upper Ordovi‐cian of central Bohemia. Morphological features of the trace, coupled with spatial interrelationships between trace and body fossils, provide evidence that the brittle star represents the trace‐maker of this Asteriacites. The cubichnial burrows probably represent negative phototaxis among the ophiuroids.

The Ichnogenus Gastrochaenolites and Its Tracemakers from Firmgrounds of the Bohemian Cretaceous Basin (Czech Republic)

Gastrochaenolites ornatus Kelly and Bromley 1984 occurs on the sub-Cretaceous unconformity surface and intra-Cretaceous omission surfaces in the area of Brandys nad Labem (central Bohemia). A variety of substrates (Proterozoic shales, Ordovician claystones and siltstones, and poorly lithified Cenomanian sandstones) were affected by the same biogenic activity. Considering the mode of construction and preservation of trace fossils, all can be considered as firmgrounds. Some specimens contain tracemakers preserved in situ, represented by thick-ribbed molluscs (cf. Myopholas sp.).

Modern and fossil traces in terrestrial lithic substrates

A number of biogenic processes leads to the formation of distinctive traces in terrestrial lithic substrates. These include: burrowing by vertebrates in moderately lithified rocks; scraping by mammals; smoothing and polishing of limestone surfaces by the locomotion of mammals; excavation by bees, wasps, and ants producing nesting and dwelling tunnels; dissolution of limestone surfaces by terrestrial snails; endolithic activity of fungi, algae, and lichens on subaerial rock surfaces; root corrosion; etc. Processes of biochemical weathering, biophysical erosion, and enlargement of cracks and fissures by the pressure of plant roots do not leave distinctive traces and therefore lie outside the ichnological realm. The fossil preservation of terrestrial bioerosional traces is expected to be uncommon. Nevertheless, various possible means of preservation must be considered, such as by rapid burial by volcanic material, by fluvial sediments, by travertine or tufa, by loess, “conservation”; in caves, case hardening of surfaces of porous rocks, and preservation of subsoil traces below fossil soils.

Terrestrial insect bioerosion and the possibilities of its fossilization (Holocene to recent, Czech republic)

Cylindrical tunnels, representing bees nests, are present at and immediately beneath exposed surfaces of Late Cretaceous castellated sandstones in the Czech Republic. The tunnels originated either in weathered rock of overhanging surfaces, or in a thin layer of weathered sandstone formed between hard opaline crusts on rock surfaces and material not affected strongly by recent exogenic processes. Degraded rock crusts, which may bear parts of the biogenic structures, are present in sandy talus deposits usually representing all of the Holocene. Insect “borings” within lithified substrates in terrestrial settings are an unusual phenomenon; their fossilization potential in the Holocene sediments of the Bohemian castellated rocks may be relatively high.

Evidence of Predation on the Rugose Coral Calceola sandalina (Devonian, Czech Republic)

A specimen of Calceola sandalina (Linne 1771) from the Givetian of the Czech Republic shows severe injury on its right side when observed from its cardinal side. Approximately one-half of the counter side is missing between the counter septum and the alar corallite angle. The injury is healed within the calice, as visible also on deformed septa close to injury, while the outer flat ventral side shows no signs of healing. The operculum is not preserved but the damage clearly must have affected it. It is difficult to envision how such damage might have occurred by abiotic means in a rather low-energy environment without the influx of grains larger than silt. We consider the injury a result of attack by a predator. When speculating on the animal capable of producing such injury, one must consider preferably a vertebrate with strong jaws: fish-like animals capable of durophagy (placoderms and chondrichthyans) appeared in the Devonian.