Insect trace fossils in glyptodonts from Uruguay

Abstract

The association of vertebrate remains and invertebrate traces, although less studied than other bioerosion traces, provides important paleoecological information. This report describes Cubiculum ornatum Roberts, Rogers, and Foreman 2007 Roberts, E., R. Rogers, and B. Foreman. 2007. Continental insect borings in dinosaur bone: examples from the Late Cretaceous of Madagascar and Utah. Journal of Paleontology 81(1):201–208.[Crossref], [Web of Science ®] , [Google Scholar], Osteocallis Roberts, Rogers, and Foreman 2007 Roberts, E., R. Rogers, and B. Foreman. 2007. Continental insect borings in dinosaur bone: examples from the Late Cretaceous of Madagascar and Utah. Journal of Paleontology 81(1):201–208.[Crossref], [Web of Science ®] , [Google Scholar] and other unidentified insect traces from the dermal skeletal remains of glyptodonts found in Uruguay. They come from the Fray Bentos Formation (Late Oligocene), the Camacho Formation (Late Miocene) and the Dolores Formation (Late Pleistocene-Early Holocene). The reported traces were likely made by sarcosaprophagous beetles, which indicate depositional conditions with dry episodes in a warm climate for the referred stratigraphical units.     

Symbiotic interactions in the Silurian of Baltica

Thirteen symbiotic associations occur in the Silurian of Baltica. Symbiosis was especially prominent among colonial animals, most commonly with stromatoporoids. These sponges hosted the most diverse fauna of endobiotic symbionts (including rugosans, Syringopora, ‘polychaetes’, cornulitids and lingulids). This pattern can be explained by the abundance of stromatoporoids in the Silurian of Baltica and their large skeletal volume, making them attractive hosts for smaller invertebrates. There is an evolutionary trend of an increasing number of different pairs of symbiotic taxa from the Llandovery to the Ludlow, with a remarkable increase in the Ludlow. This is likely related to an increase in the number of mutualistic taxa that could have had evolutionary advantages over organisms less amenable to symbiosis. The number of different pairs of symbiotic taxa also increased in the Wenlock, which may be linked to delayed recovery from the end‐Ordovician mass extinction.     

Precambrian trace fossils and the rise of bilaterian animals

In this attempt to synthesize present knowledge into a coherent story, the Cambrian explosion is interpreted to represent a true adaptive radiation, an event similar to Phanerozoic radiation events in principle but unique in its possibilities. A model of bilaterian evolution helps explain how this particular event involved the sudden initiation of major coelomate phyla. In many of these groups, preservable skeletons are part of the basic body plan. Biochemical‐sequence analyses indicate that acoelomates and pseudocoelomates branched off long before the coelomate radiation. The great differences between Vendian and Cambrian ichnofaunas, therefore, may be the result of a major shift in composition from Vendian acoelomate‐pseudocoelomate‐procoelomate faunas to Phanerozoic faunas dominated by new coelomate groups.     

The fish swimming trace Undichna unisulca from the Silurian of Sweden: probably the oldest vertebrate locomotion trace fossil

The fish swimming trace Undichna unisulca is reported from a sandstone block collected from the Upper Silurian (Ludlow) Burgsvik Formation of Gotland, Sweden. It represents the oldest record of a vertebrate trace (apart from coprolites), predating previous finds from the Lower Devonian by at least 10 Ma. A thelodont or acanthodian fish may have produced the sinusoidal trails with the aid of their caudal or anal fins while browsing slowly over the sediment whilst searching for food.     

Middle Jurassic trace fossils from the Ridang Formation in Sajia County,South Tibet,and their palaeoenvironmental significance

An ichnofauna consisting of 18 ichnospecies (one of them new) in 14 ichnogenera are described for the first time from the Middle Jurassic Ridang Formation in Sajia County, South Tibet. The ichnofauna can be subdivided into two ichnoassemblages in ascending stratigraphic order: the Palaeophycus–Megagrapton ichnoassemblage in the lower and middle parts of the Ridang Formation, followed by the Cosmorhaphe–Nereites–Paleodictyon ichnoassemblage in the upper Ridang Formation. Overall, the trace fossils occur in a middle–distal turbidite fan sequence, as evidenced by both sedimentological analysis and the composition of the trace fossils. Several subenvironments of the middle–distal fan system have been recognized on the basis of the spatial distribution of the trace fossils. Typically, the channel-fill deposits in the middle part of the turbidite fan lack trace fossils, the interchannel and upper channel-fill (levee) subenvironments of the middle turbidite fan contain abundant facies-crossing trace fossils, in contrast to the distal part of the turbidite fan where deep-water trace fossils are dominant. The ichnofauna is similar to typical flysch ichnofaunas from Europe and North America in characteristics, and is interpreted to represent a typical deep-sea Nereites ichnofacies. The presence of these deep-sea trace fossils therefore would suggest that a continental slope environment existed in southern Tibet during the Middle Jurassic and the study area was located in a slope-abyssal plain setting.     

Dictyodora and associated trace fossils from the Palaeozoic of Thuringia

Dictyodora occurs in the Hauptquarzit (Late Ordovician; D. zimmermanni) and Bordenschiefer (Early Carboniferous; D. liebeana) of Thuringia, East Germany. It is absent in the Early Devonian Nereitenquarzit, and analysis of the trace fossil assemblages points to environmental partitioning within the ‘deep-sea’Nereites Association. The Carboniferous Dictyodora was much larger than the Early Palaeozoic forms and had a long respiratory (?) wall organ. This may have been an adaptation to feeding deeper in anoxic sediments, and the animal developed large ‘parapodia’ to effect its progression through the sediment.     

Diverse tiering patterns in Paleogene flysch trace fossils,Magura nappe,Carpathian Mountains,Poland

Diversified tiering patterns of trace fossils were observed in three Paleogene lithostratigraphic units of the Magura nappe: the Szczawnica Formation (Paleocene‐early Eocene); the Belove?a beds (middle Eocene); and the Piwniczna Sandstone Member of the Magura Formation (middle‐upper Eocene). Sediments of the first unit were deposited under oxygen‐poor conditions, and those of the second and third units under well‐aerated conditions. Thick‐bedded turbidites and fluxoturbidites of the third unit accumulated quickly, in contrast to ‘normal flysch’ of the first and second units. Analyses of tiering patterns show a thickening of tiers following the improvement of sediment oxygenation. Slowly accumulated deposits of ‘normal’ flysch exhibit a more mature, well‐developed tiering pattern than those which accumulated quickly.     

Juvenile chum salmon consumption of zooplankton in marine waters of southeastern Alaska: a bioenergetics approach to implications of hatchery stock interactions

Bioenergetics modeling was used to estimate zooplankton prey consumption of hatchery and unmarked stocks of juvenile chum salmon (Oncorhynchus keta) migrating seaward in littoral (nearshore) and neritic (epipelagic offshore) marine habitats of southeastern Alaska. A series of model runs were completed using biophysical data collected in Icy Strait, a regional salmon migration corridor, in May, June, July, August, and September of 2001. These data included a temperature (1-m surface versus surface to 20-m average), zooplankton standing crop (surface to 20-m depth versus entire water column), chum salmon diet (percent weight of prey type consumed), energy densities, and weight. Known numbers of hatchery releases were used in a cohort reconstruction model to estimate total abundance of hatchery and wild chum salmon in the northern region of southeastern Alaska, given average survival to adults and for two different (low and high) early marine littoral mortality rate assumptions. Total prey consumption was relatively insensitive to temperature differences associated with the depths potentially utilized by juvenile chum salmon. However, the magnitudes and temporal patterns of total prey consumed differed dramatically between the low and high mortality rate assumptions. Daily consumption rates from the bioenergetics model and CPUE abundance from sampling in Icy Strait were used to estimate amount and percentage of zooplankton standing crop consumed by mixed stocks of chum salmon. We estimated that only a small percentage of the available zooplankton was consumed by juvenile chum salmon, even during peak abundances of marked hatchery and unmarked mixed stocks in July. Total daily consumption of zooplankton by all stock groups of juvenile chum salmon was estimated to be between 330 and 1764 g/km²d¹ from June to September in the neritic habitat of Icy Strait. As with any modeling exercise, model outputs can be misleading if input parameters and underlying assumptions are not valid; therefore, additional studies are warranted, especially to determine physiological input parameters, and to improve abundance and mortality estimates specific to juvenile chum salmon. Future bioenergetics modeling is also needed to evaluate consumption by the highly abundant, vertically migrating planktivorous that co-occurred in our study; we suggest that these fishes have a greater impact on the zooplankton standing crop in Icy Strait than do hatchery stock groups of juvenile chum salmon.     

Walking on ashes: insect trace fossils from Laetoli indicate poor grass cover associated with early hominin environments

More than 4000 insect trace fossils collected in recent years from Pliocene deposits at Laetoli in northern Tanzania provide new insights on early hominin palaeoenvironments. These trace fossils include: Fictovichnus gobiensis, Coprinisphaera murguiai, C. kheprii, Coprinisphaera ispp., Quirogaichnus isp., Teisseirei linguatus isp. nov., Celliforma ritchiei isp. nov., C. spirifer, C. germanica, C. cfr. curvata, Celliforma ispp., Rosellichnus isp., Vondrichnus planoglobus, Laetolichnus kwekai igen. et isp. nov. and Krausichnidae indet. They reveal that at least one species of moth, three dung beetles and five other coleopterans, nine taxa of solitary bees, and an indeterminate number of taxa of termites inhabited the Lower Laetolil environments. The Upper Laetolil environments, which have yielded a rich diversity of vertebrate fossils, including the early hominin Australopithecus afarensis and its putative footprints, supported several taxa of termites, one dung beetle, five other coleopterans, and eleven taxa of bees. The Upper Ndolanya environments, which have yielded the hominin Paranthropus aethiopicus, record four taxa of dung beetles, four other coleopterans, and two taxa of bees. The record of larval mortality and lack of intruder activity, revealed by the absence of emergence and intruder traces, may be associated with the anoxic/hypoxic conditions caused by the instantaneous burial of soils under thick volcanic ashes. The record of the Celliforma Ichnofacies in the Upper Laetolil environments indicates the dominance of shrubland to woodland with limited grass cover. This is supported also by the absence of Coprinisphaera, which suggests a scarcity of fresh grasses and a low abundance of large mammal grazers.     

An ethological framework for animal bioerosion trace fossils upon mineral substrates with proposal of a new class, fixichnia

Animal bioerosion trace fossils upon mineral substrates are analyzed from the point of view of the Seilacherian ethological classification. Several of the currently accepted ethological classes: cubichnia, fugichnia, repichnia, fodinichnia, agrichnia, calichnia and aedificichnia are not represented in these substrates. This fact points out a lower behavioral diversity of hard substrate trace fossils when compared with soft sediment trace fossils. Bioerosion traces can be classified in just five classes: domichnia, pascichnia, equilibrichnia, praedichnia and fixichnia. Fixichnia is here erected to gather superficial etching scars resulting from the anchoring of fixation of sessile epiliths by means of a soft or skeletal body part. Praedichnia and fixichnia are exclusive of the bioerosion realm.     

Trace fossils from arenig flysch sediments of eire and their bearing on the early colonisation of the deep seas

A sequence of Lower Ordovician (Arenig) turbidites in Co. Wexford, Eire, has yielded one of the earliest diverse ichnofaunas yet recorded from deep water sediments comprising: Chondrites, Glockerichnus, Gordia, Helminthopsis, Lorenzinia, Neonereites, Palaeophycus, Paleodictyon, Planolites, Sublorenzinia, Taenidium, Taphrhelminthopsis, Teichichnus and Tomaculum. This ichnofauna is critical in any analysis of the colonisation of the deep seas by trace fossil‐producing animals.

A world‐wide review shows that the earliest trace fossils are mainly from Late Precambrian shelf sea environments, but many more evolved during very rapid diversification in the pre‐trilobite Lower Cambrian.

There was little increase in diversity in shallow water after the Lower Cambrian but a progressive colonisation of the deep ocean took place and this accelerated during the Ordovician, when the main lineages of deep sea trace fossils were established there. Rosetted, patterned, meandering and simple spiral forms evolved in shallow water in the Upper Precambrian and pre‐trilobite Lower Cambrian and only later migrated into the deep sea, whereas complex, closely programmed, spiral traces may have evolved there.     

Small shelly fossils and trace fossils near the Precambrian-Cambrian boundary in the Yukon Territory, Canada

In the past an ‘explosion’ in diversity and abundance of small shelly fossils and of trace fossils has served to mark the base of the Cambrian. However, no evidence has been presented to prove that the ‘explosions’ of the two groups were synchronous. We describe small shelly fossils and trace fossils from the same phosphatic limestone beds that indicate that the two events were separate in time. The small shelly fossils are Anabarites trisulcatus, Hyolithellus cf. H. isiticus, Microcornus? sp., Protohertzina anabarica, P. unguliformis, P. sp. A, Pseudorthotheca sp. A, Rushtonia? sp. A, four types of tuberculate plates and one type of reticulate plate. These fossils represent a restricted, ‘pre-explosion’ fauna and are assigned to the Anabarites-Circotheca-Protohertzina Assemblage Zone, an uppermost Precambrian zone in the Meishucun Stage, Yunnan Province, China. A point at the top of this zone has received strong international endorsement for future designation as the base of the Cambrian. Associated with the small shelly fossils are the trace fossils Cruziana sp. A, Cruziana? sp. B, Rusophycus sp. A, Palaeophycus rubdark and arthropod scratch marks. If found in isolation, this trace fossil assemblage would be considered as post-Precambrian because it includes large, highly organized arthropod traces that are traditionally accepted as occurring above the trace fossil ‘explosion’. We therefore conclude that the trace fossil ‘explosion’ predates the small shelly fossil ‘explosion’. If the proposed location of the base of the Cambrian in Yunnan is accepted, the small shelly fossil ‘explosion’ concept and its relationship to the boundary would not be greatly modified. The trace fossil ‘explosion’, however, would no longer indicate the base of the Cambrian and the ranges of some trace fossils would be extended into the Precambrian.     

Swimming trace of a coelacanth fish from the Lower Keuper of south-west Germany

Parundichna schoelli igen. nov., isp. nov. from the Middle Triassic (Ladinian) Lower Keuper of Rot am See (Baden-Württemberg, Germany) consists of clusters of sigmoidal scratches symmetrically arranged in a plaited pattern. It is here interpreted as the swimming trace of a large coelacanth fish. In contrast to ichnospecies of Undichna there is no unpaired groove left by the tail fin. Instead, the sets of parallel scratches resulted from the pendulum motion of two pairs of appendages, the pectoral and pelvic fins, which acted in alternation, as in tetrapods. This strange mode of swimming is compared to films of modern Latimeria and to computer simulations; it probably corresponds to a particular foraging behaviour. The presence of fittingly-sized coelacanths is documented in coeval carbonates (Alberti-Bank) by disarticulated skeletal elements. Since the Lower Keuper represents a fluvial and estuarine facies of the receding Muschelkalk sea, we cannot be sure whether this trace was made in a marine or freshwater environment.     

Mammalian biogeography of the Alexander Archipelago of Alaska: a north temperate nested fauna

Aim A large number of studies have analysed the distribution of mammals within archipelagos, yet few have focused on islands that were heavily glaciated and subsequently colonized following deglaciation. Location We explored the relative effects of island area and isolation on faunal composition based on twenty-three mammalian taxa of twenty-four islands of the Alexander Archipelago, Southeast Alaska. Methods We used regression of log-transformed variables and several indices of nestedness. Results These faunas showed significant nested structure using tests of nestedness and regression models. Unlike most landbridge and mainland archipelagos studied previously, isolation appears to be the primary factor determining patterns of species richness. Main conclusions Colonization ability of particular taxa, rather than extinction, has determined this nested structure. We suggest that other higher latitude archipelagos may show similar historical patterns.     

Lower Cretaceous (Albian) shell-armoured and associated echinoid trace fossils from the Sácaras Formation, Serra Gelada area, southeast Spain

The Sácaras Formation (Albian, Lower Cretaceous) of the Serra Gelada succession (Prebetic of Alicante), southeast Spain, comprises carbonate‐rich, upwards thickening parasequences in which many types of trace fossils have been identified. The present study focuses on two types of tubular trace fossil characterized by features of their external coating. The first type is represented by a shell‐covered, structured trace fossil, up to 4?cm in diameter and 40?cm in length, built horizontally, from rectilinear (type 1) to gently curved (type 2), which envelopes an unstructured pipe of grey silty sediment. The coating is characterized by imbricated, flat particles, mainly orbitolinid foraminifers and other planar bioclasts, forming thin concentric layers; in cross section the bioclasts produce a typical plumed structure. This trace fossil represents a new ichnogenus and ichnospecies, here named Ereipichnus geladensis. Particle arrangement of the external coating is similar to that of terebelloid tubes, but Ereipichnus is a horizontal trace fossil, whereas structured worm tubes are vertical. The second type is a grain‐coated trace fossil, tubular in shape, with a simple internal structure. The coating is often reddish with respect to the neighbouring dark grey sediment and shows a slightly coarser‐grained texture, which envelopes the internal muddy pipe. This type, which yielded echinoids, was produced by irregular or heart‐shaped sea‐urchins (spatangoids) and is attributed to Scolicia or Cardioichnus. Facies analysis of the Serra Gelada succession with Ereipichnus and Scolicia or Cardioichnus locally shows other types of branched trace fossils (primarily represented by different forms of Thalassinoides) and bioturbation is developed in tiers, increasing upwards in abundance and diversity.     

Environmental distribution of trace fossils in the Jurassic of Kachchh (Western India)

Summary Trace fossils occur abundantly in Middle Jurassic rocks of the Kachchh Basin. They are found in environments ranging from beach sequences down to central parts of the basin. For stratinomic reasons, they are particularly well preserved in storm deposits. Their distribution pattern exhibits a clear relationship to the hydrodynamic conditions and, secondarily, to bathymetry, and follows the classic ichnofacies concept ofSeilacher (1967). High energy nearshore areas and submarine shoals are represented by members of the Skolithos ichnofacies such asOphiomorpha nodosa, Arenicolites, Diplocraterion parallelum, andRhizocorallium jenense. The storm-influenced ramp contains both members of the Cruziana ichnofacies (e.g.Rhizocorallium irregulare, Thalassinoides suevicus, Taenidium serpentinum, Chondrites) and the Skolithos ichnofacies (in particularOphiomorpha). The former were produced during interstorm phases, the latter are of post-storm origin. Carbonate ramp environments of low to intermediate energy also contain members of the Cruziana ichnofacies, whilst equivalent siliciclastic environments are characterized by a low-diversity Zoophycos ichnofacies. Low energy basinal environments of fine-grained substrates contain an impoverished Cruziana ichnofacies consisting ofChondrites, Trichichnus andThalassinoides suevicus. 32 ichnotaxa are briefly described, among themSphaerichnus lobatus ichnogen. et ichnosp. nov.     

Trace fossils from the Podhale Flysch Basin, Poland - an example of ecologically-based lithocorrelation

Certain ichnogenera from the Podhale Flysch Basin do not occur randomly, but are grouped in distinct horizons, which are useful in mapping. The position of certain tuffite beds proves an approximate isochronism of those trace fossil horizons. Changes of the life conditions, among them especially oxygenation of the sea bottom, were responsible for that ichnologic differentiation. Profuse Occurrences of Taphrhelminthopsis are mainly connected with the presence of lighter, bluish shales, which indicates a well-oxygenated bottom. More distal and frequent sedimentation of turbidites could positively influence the preser-vational potential of the surface forms (very good state of preservation of Taphrhelminthopsis suggests that preservation of surface forms was frequent in the flysch basin), but the O₂ condition was the main controlling factor for the occurrences of ichnofauna. Most discriminating were trace makers of pre-depositional (mud-dwelling) Taphrhelminthopsis , and they were most probably irregular echinoids, while soft-bodied trace makers of pre- and post-depositional Planolites (post-depositional means sand-dwellers) were the most tolerant ones. An increased level of biological activity connected with a shift in the OMZ could have been the reason why Taphrhelminthopsis became so profuse in one period. Concerning preservational problems, some complications in determining pre- and post-depositional forms in the case of composite beds are presented.     

Deep-water trace fossils in the Ilfjellet rift basin (Middle Ordovician), central Norwegian Caledonides

The late Early to early Middle Ordovician Fjellvollen Formation, Central Norwegian Caledonides, is a part of the Ilfjellet Group volcano-sedimentary succession formed in a rift basin that opened along the Laurentian margin. Depositional facies and trace fossils indicate the Nereites ichnofacies, typically found in distal turbidites and deep marine deposits. The recovered trace fossils include ?Alcyonidiopsis, Chondrites, Dictyodora, Gordia, Helminthoidichnites, Macaronichnus, Monomorphichnus, Nereites, Oikobesalon, Palaeophycus, Protovirgularia and Treptichnus. No body-fossils have been reported from the Fjellvollen Formation, but the trace fossils indicate the presence of varied epi- and infaunas of arthropods, bivalves, gastropods and polychaets. The abundance of meandering and looping trace fossils is comparable to what is found in the inferrably time-equivalent Vuddudalen Group farther north, although lack of graphoglyptids like Megagrapton in the Fjellvollen Formation may indicate more proximal, unstable depositional conditions in fan-fringe and adjacent basin-plain settings.     

Preservation of soft tissues in Silurian graptolites from Latvia

The contractile stalks of graptoloid zooids are preserved as organic carbon residues in thecae of the middle Llandovery graptoloid graptolites Rastrites geinitzii and Neolagarograptus? sp. from the Aizpute‐41 core, Latvia. The contractile stalks are surrounded by equant pyrite crystals, resulting in three‐dimensional preservation of the graptolite rhabdosomes, and are associated with sediment of similar composition to, and derived from, the adjacent matrix. Matrix entered the thecae after pyrite crystal growth and filled some of the space left by collapse of the contractile stalks and some intercrystalline cavities; other space is partially infilled by diagenetic minerals. The contractile stalks are parallel‐sided and occupy up to one‐half the metathecal width, which is not inconsistent, assuming post‐mortem shrinkage, with the suggestion that graptoloid zooids filled their thecal tubes in life. The location of the preserved soft tissues, towards the distal ends of the metathecae, is very different from that predicted by decay experiments on the extant pterobranch hemichordate Rhabdopleura; the latter's soft tissues may thus not be a reliable analogue for those of these Silurian graptoloids.