New Ordovician fossils (bivalves, trilobites, brachiopods) from southern Jordan and re-evaluation of the regional Ordovician body fossil record

The Darriwilian Hiswah fauna of western Gondwana (Jordan): Biostratigraphy, palaeogeography and palaeoecology

Sauropod tracks from the Middle Jurassic Chuanjie Formation of Yunnan Province and the pre-Cretaceous sauropodomorph trackways from China

Although tortoises (Testudinidae) are a familiar clade of reptiles, with a body fossil record extending to at least the Eocene, hitherto no tortoise ichnosites have been described. Here, a number of sites attributed to tortoise trackmakers are identified within Pleistocene aeolianites on South Africa's Cape south coast. These date from late Marine Isotope Stage 6 to Marine Isotope Stage 4. The findings indicate large trackmakers, with evidence of a trackmaker length of more than a meter—substantially longer than the largest extant tortoises in southern Africa. This suggests either the presence of an extinct very large tortoise species, or that Pleistocene leopard tortoises in the region were larger than their descendants. Variations in substrate properties are responsible for a variety of track and trace forms. A mismatch exists between the reported ichnological evidence for large tortoises, and the regional archaeological and body fossil records, which almost exclusively comprise smaller tortoises. The findings illustrate the potential of ichnology to complement and augment the paleontological and archaeological records.

Annelids are a phylum of segmented bilaterian animals that have become important components of ecosystems spanning terrestrial realms to the deep sea. Annelids are remarkably diverse, possessing high taxonomic diversity and exceptional morphological disparity, and have evolved numerous feeding strategies and ecologies. Their interrelationships and evolution have been the source of much controversy over the past century with the composition of the annelid crown group, the relationship of major groups and the body plan of the ancestral annelid having undergone major recent revisions. There is a convincing body of molecular evidence that polychaetes form a paraphyletic grade and that clitellates are derived polychaetes. The earliest stem group annelids from Cambrian Lagerstätten are errant, epibenthic polychaetes, confirming that biramous parapodia, head appendages and diverse, simple chaetae are primitive for annelids. Current evidence from molecular clocks and the fossil record suggest that crown group annelids are a Late Cambrian – Ordovician radiation, with clitellates radiating in the Late Palaeozoic. Their body fossil record is largely confined to deposits showing exceptional preservation and is punctuated by the acquisition of hard parts in major groups. The discovery of an Ordovician fossil with soft tissues has shown that machaeridians are in fact a clade of crown polychaetes. They were in existence for more than 200 million years and possess unique calcitic dorsal armour, allowing their mode of life and phylogeny to be interpreted in the context of the annelid body plan. We identify a novel clade of machaeridians, the Cuniculepadida, which exhibit a series of adaptations for burrowing.

IN spite of its relatively small land area, New Zealand contains a remarkably complete fossil record. Up to the present the Carboniferous and the Silurian have been the only two Phanerozoic geological periods not known to be represented by fossils. The apparent absence of Silurian fossils has been considered strange because upper Ordovician and lower Devonian fossils are present in sedimentary sequences in north-west Nelson, South Island, which do not seem to be interrupted by regional unconformity, and which therefore presumably contained sediments of Silurian age1. The conclusive identification of Silurian fossils from north-west Nelson is therefore of considerable interest.

Dinosaur tracks are a key means of determining the palaeoecology and distribution of dinosaurs through time. They provide an information source that is highly complementary to the body (skeletal) fossil record, but differ in preserving direct evidence of the animals’ interactions with their environment. The UK has a rich history of c. 200 years of dinosaur track discovery, but no recent synthesis exists. Here, we present a new dataset of dinosaur tracks in the UK. This dataset shows a close correlation between the distribution of terrestrial sediments and the preservation of dinosaur tracks through the Mesozoic, providing discrete snapshots into dinosaur communities in the Late Triassic, Mid-Jurassic and Early Cretaceous. The dinosaur track record shows similar broad patterns of diversity and relative abundance of the major dinosaur groups (Theropoda, Sauropodomorpha, Ornithopoda and Thyreophora) through time to the body fossil record, although it differs in that body fossils are also found (albeit infrequently) in marine sediments. There is a broad trend towards higher numbers of track occurrences through time and a notable increase in the relative abundance of ornithopod tracks following the Jurassic–Cretaceous boundary. The track record remains an underutilized resource with the potential to provide a much fuller view of Mesozoic dinosaur ecosystems. Supplementary material: Our new UK dinosaur track database, the PBDB body fossil record and the relative abundance of non-marine/marine rocks in England and Wales used in this study are provided in Supplementary Tables 1–3, respectively, the R-code used to analyse the data and generate Figures 2 and 3 and Supplementary Figures 1–4 is given in Supplementary Information 1 and 2, and are available at https://doi.org/10.6084/m9.figshare.c.6606634

Tetrapod footprints have a fossil record in rocks of Devonian-Neogene age. Three principal factors limit their use in biostratigraphy and biochronology (palichnostratigraphy): invalid ichnotaxa based on extramorphological variants, slow apparent evolutionary turnover rates and facies restrictions. The ichnotaxonomy of tetrapod footprints has generally been oversplit, largely due to a failure to appreciate extramorphological variation. Thus, many tetrapod footprint ichnogenera and most ichnospecies are useless phantom taxa that confound biostratigraphic correlation and biochronological subdivision. Tracks rarely allow identification of a genus or species known from the body fossil record. Indeed, almost all tetrapod footprint ichnogenera are equivalent to a family or a higher taxon (order, superorder, etc.) based on body fossils. This means that ichnogenera necessarily have much longer temporal ranges and therefore slower apparent evolutionary turnover rates than do body fossil genera. Because of this, footprints cannot provide as refined a subdivision of geological time as do body fossils. The tetrapod footprint record is much more facies controlled than the tetrapod body fossil record. The relatively narrow facies window for track preservation, and the fact that tracks are almost never transported, redeposited or reworked, limits the facies that can be correlated with any track-based biostratigraphy. A Devonian-Neogene global biochronology based on tetrapod footprints generally resolves geologic time about 20 to 50 percent as well as does the tetrapod body fossil record. The following globally recognizable time intervals can be based on the track record: (1) Late Devonian; (2) Mississippian; (3) Early-Middle Pennsylvanian; (4) Late Pennsylvanian; (5) Early Permian; (6) Late Permian; (7) Early-Middle Triassic; (8) late Middle Triassic; (9) Late Triassic; (10) Early Jurassic; (11) Middle-Late Jurassic; (12) Early Cretaceous; (13) Late Cretaceous; (14) Paleogene; (15) Neogene. Tetrapod footprints are most valuable in establishing biostratigraphic datum points, and this is their primary value to understanding the stratigraphic (temporal) dimension of tetrapod evolution.

Micro‐computed tomography (μCT) scanning now represents a standard tool for non‐destructive study of internal or concealed structure in fossils. Here we report on otoliths found in situ during routine μCT scanning of three‐dimensionally preserved skulls of Palaeogene and Cretaceous fishes. Comparisons are made with isolated otolith‐based taxa to attempt correlations between the body fossil and otolith fossil records. In situ otoliths previously extracted mechanically from specimens of Apogon macrolepis and Dentex laekeniensis match our μCT models. In some cases, we find a high degree of congruence between previously independent taxonomic placements for otolith and skeletal remains (Rhinocephalus, Osmeroides, Hoplopteryx). Unexpectedly, in situ otoliths of the aulopiform Apateodus match isolated otoliths of Late Cretaceous age previously interpreted as belonging to gempylids, a group of percomorph fishes that do not appear in the body fossil record until the Palaeogene. This striking example of convergence suggests constraints on otolith geometry in pelagic predators. The otoliths of Apateodus show a primitive geometry for aulopiforms and lack the derived features of Alepisauroidea, the lizardfish clade to which the genus is often attributed. In situ otoliths of Early Cretaceous fishes (Apsopelix and an unidentified taxon) are not well preserved, and we are unable to identify clear correlations with isolated otolith morphologies. We conclude that the preservation of otoliths suitable for μCT scanning appears to be intimately connected with the taphonomic history, lithological characteristics of surrounding matrix, and syn‐ and postdepositional diagenetic effects.

The giant Cape zebra (Equus capensis) is one of the extinct Quaternary large mammal species of southern Africa, and the largest equid from the Quaternary of Africa. Twenty-six Pleistocene equid tracksites have been identified in aeolianites on the Cape south coast of South Africa. An age range of 161 ± 12 ka to 43 ± 4 ka has been established through Optically Stimulated Luminescence. More than half of the sites contain large-equid tracks, representing the first ichnosites attributed to E. capensis. Smaller equid tracks may have been registered by the quagga (E. quagga quagga). The abundance of E. capensis tracksites on the Cape south coast contrasts with the paucity of body fossils of the species from the region, contrasting with the impression obtained from the body fossil record that E. capensis was predominantly a west coast species in the region. The new data illustrate the capacity of the body fossil and trace fossil records to complement each other. The loss of suitable habitat provided by the Palaeo-Agulhas Plain was probably a contributing factor in the extinction of this large-bodied grazer. A long trackway at Driefontein, attributed to E. capensis, adds to a sparse global record of fossil horse trackways.

The fossil record provides the only direct evidence of temporal trends in biodiversity over evolutionary timescales. Studies of biodiversity using the fossil record are, however, largely limited to discussions of taxonomic and/or morphological diversity. Behavioural and physiological traits that are likely to be under strong selection are largely obscured from the body fossil record. Similar problems exist in modern ecosystems where animals are difficult to access. In this review, we illustrate some of the common conceptual and methodological ground shared between those studying behavioural ecology in deep time and in inaccessible modern ecosystems. We discuss emerging ecogeochemical methods used to explore population connectivity and genetic drift, life-history traits and field metabolic rate and discuss some of the additional problems associated with applying these methods in deep time.

East of Still Bay on the Cape south coast of South Africa lies a rugged, remote stretch of sea cliffs that expose Late Pleistocene aeolianites. A zone of dense concentration of fossil tracks occurs within this area. Two large rocks, which we call Roberts Rock and Megafauna Rock, were identified ~400 metres apart. These rocks contained a variety of trackways, individual tracks, burrow traces and invertebrate trace fossils on multiple bedding planes. Both rocks were found ex situ, but their context could be determined. Roberts Rock has subsequently slid into the ocean, and Megafauna Rock lies at the base of a coastal cliff. Probable trackmakers include elephant, long-horned buffalo, giant Cape horse, rhinoceros, medium and small artiodactyls, golden mole, birds and invertebrates. Dating studies at an adjacent site, which is comparable to the stratigraphy described here, indicate that both rocks were most likely deposited in Marine Isotope Stage 5e (~128–116 ka). Analysis and description of these tracksites confirms the potential of ichnology to complement the skeletal fossil record and to enhance the understanding of Pleistocene life in southern Africa. The ephemeral nature of such tracksites makes repeated visits to this coastline desirable, both to monitor the fate of known sites and to search for newly exposed trace fossil surfaces.
 Significance:
 
 Roberts Rock and Megafauna Rock are two remarkable fossil tracksites on the Cape south coast, which contain tracks of four members of the Late Pleistocene megafauna. They provide a glimpse of Pleistocene dune life and suggest an area teeming with large mammals.
 These tracks were made on dune surfaces near an interface between the grassland of the Palaeo-Agulhas Plain and the inland Fynbos–Strandveld–Renosterveld. Faunal assemblages from both vegetation zones might therefore be recorded.
 The trace fossil record and body fossil record both have inherent biases, but have the potential to independently provide complementary information on palaeofaunal composition.
 The two rocks have provided the first South African records of fossil elephant tracks (as first described by Dave Roberts and colleagues in 2008), the first rhinoceros track and the first extinct giant Cape horse track, and track evidence of the extinct long-horned buffalo.
 Roberts Rock has slumped into the ocean, and it provides an example of the fate of many exposed tracksites. Conversely, new sites frequently become exposed. This scenario stresses the need for regular ichnological surveys along this track-rich coastline to monitor existing sites and to search for new sites.

The Carboniferous Joggins Fossil Cliffs UNESCO World Heritage Site in Nova Scotia, Canada, has long been known for its extensive paleobiodiversity. The ichnofossil record at Joggins is less known than the body fossil record. Amongst the extensive ichnological collections of the late citizen-scientist Donald Reid is a morphologically unique shrimp-shaped cubichnium (resting trace). The trace fossil is associated with a faint invertebrate trackway that leads up to the resting trace and establishes its identification as an invertebrate resting trace. The trace fossil was recovered from the upper Joggins Formation (876 m above the base), and was found in finegrained, rippled sandstones interpreted to be from an open-water to poorly drained lithofacies assemblage transition. The trace fossil slab studied here also has examples of the invertebrate resting traces Selenichnites and Rusophycus preserved in convex hyporelief; these traces are commonly attributed to horseshoe crabs and crustaceans, respectively. They co-occur in the same stratigraphic horizon with Kouphichnium trackways, interpreted to be produced by xiphosurans. The upper Joggins Formation has previously yielded body fossils of Pygocephalus shrimp preserved in organic-rich limestones and sideritic-ironstone nodules. Pygocephalus body fossils are common at Joggins, but no trace fossils have been assigned to this invertebrate, perhaps having gone unrecognized until now. The trace fossil newly described here as Pygocephalichnium reidi is interpreted to have been produced by a Pygocephalus shrimp based on its morphological similarities to known body fossils from the Joggins Formation, and we propose that this new trace fossil morphology warrants a new ichnotaxon, Pygocephalichnium reidi.

Ichnofabrics in the sediments drilled at Site 605 reflect environmental changes. Long-term changes allow the section to be differentiated into four units, and short-term fluctuations define cycles in the range of several decimeters. The composition of the ichnofabrics is controlled by the availability of nutrients within the sediment (reflecting productivity in the surface waters and the sedimentation rate) and by oxygen content within the respiration water (related to deepwater circulation patterns as well as to the organic carbon content of the sediment). INTRODUCTION Many studies of deep-sea environments relate biogenic structures to ecologic conditions (e.g., Ekdale, 1977; Ekdale et al., 1984; Wetzel, 1981, 1983a, b). In deep-sea sediments, trace fossils can provide valuable information on the paleoecology and geologic history of the benthic macro fauna. This is important in that most macrorganisms living in the deep-sea environment are not preserved in the body fossil record (Ekdale, 1977). This study is based on observations of biogenic sedimentary structures in sediments drilled at Deep Sea Drilling Project Site 605, which is situated on the upper continental rise off New Jersey at about 2,200 m water depth (Fig. 1). The bottom of the hole was 816.7 m below the seafloor; the upper 154 m were washed, but rotary drilling recovered the lower 662 m of sediment. The sediments drilled at Site 605 are heavily bioturbated. The deposits were normally several times reworked by organisms; thus, the continuing response of the burrowing macro fauna to environmental changes is well preserved, allowing a reconstruction of past environments. Five lithologic units were distinguished at Site 605: Unit I, 198 m of Pleistocene gray, silt-rich clay; Unit II, 153 m of lower to middle Eocene biosiliceous nannofossil chalk rich in radiolarians and diatoms; Unit HI, 214 m of lower to middle Eocene greenish gray nannofossil limestone with varying amounts of foraminifers and calcified radiolarians; Unit IV, 176 m of Paleocene dark greenish gray clayey nannofossil marls and limestones; and Unit V, 77 m of lower Paleocene to Maestrichtian olive gray, clayey limestone. An unconformity occurs between the upper Eocene and Pliocene. Throughout the drilled section, carbonate content is usually greater than 60%. The organic carbon content varies between 0.1 and 0.6% (with a mean of 0.22%). The (compacted) sedimentation rates vary from 2 to 4 cm/10 yr. for Units III, IV, and V, whereas Unit II has van Hinte, J. E., Wise, S. W., Jr., et al., Init. Repts. DSDP, 93: Washington (U.S. Govt. Printing Office). 2 Address: Geologisch-Palaontologisches Institut der Universitat, Sigwartstrase 10, D 7400 Tubingen, Federal Republic of Germany. a markedly higher rate with an average of more than 10 cm/10 yr. The Paleogene section shows evidence of cyclic sedimentation, especially in Units III and IV. An unusually high biosiliceous productivity began during the Eocene Epoch (Units II and III), reaching a constant high level in Unit II. METHODS Biogenic structures were identified by means of typical cross-sections. Because such identifications may be subjective, the trace fossils were defined only at the ichnogenus level (Hantzschel, 1965, 1975). Sometimes a subdivision of one ichnogenus was possible when distinct maxima in diameter distribution and differences in sediment infill were found (Wetzel, 1981). In general, two types of biogenic sedimentary structures can be distinguished: (1) trace fossils with a well-defined shape and sharp and distinct outlines and (2) biodeformational structures, which have indistinct outlines and features and which destroy preexisting structures. This study is based on visual observations of wet cores. This is important to note, because other methods of observation, for example, X-ray radiography (Wetzel, 1981), wetting with oil (Bromley, 1981), or staining (Risk and Szczuczko, 1977), allow the recognition of more types of trace fossils but fewer biodeformational structures. As an additional complication, diagenesis may enhance certain burrow types, whereas others are more or less masked. In this description only trace fossils are discussed. In Hole 605 sediments, trace fossils at and near the sediment surface had no chance of being preserved in the fossil record; hence, only more deeply burrowed traces are considered. RESULTS Description of Trace Fossils Chondrites Chondrites are three-dimensional burrow systems which normally branch downward into the sediment at angles of 30-60°. They are simple tunnels or wall-lined tubes (Wetzel, 1981) that consist of (1) a connection from the seafloor to (2) a typically branched lower part. In general, tunnels or tubes become more horizontal with depth below the surface of the seafloor (Fig. 2). Different types were identified in the sediments drilled at Site 605 by their differing diameter and sediment fill, as suggested by Wetzel (1979, 1981). Chondrites in Hole 605 also had reworked other burrows (= composite burrows; Fig. 3).

BackgroundArchosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3–247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains.Methodology/Principal FindingsWe redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the ‘sail’ of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation.Conclusions/SignificanceComprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian–Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs.

Antiquity of cancer.