Fossil Lagerstatte Research Articles

A silicified Todea trunk (Osmundaceae) from the Eocene of Patagonia

The Osmundaceae family is the sister group to all other extant leptosporangiate ferns. Its rich fossil record has enabled detailed reconstructions of the evolutionary history of the group. Fossil evidence for today’s Southern Hemisphere subtribe Todeinae, however, has been difficult to accumulate, with only two unambiguous fossil occurrences of modern Todea. Here, we describe a silicified Todea stem from the Eocene Laguna del Hunco lagerstatte of Patagonia. The stem contains a heterogeneous outer cortex with distinct fibrous rings surrounding the leaf traces, indicative of subtribe Todeinae; nests of thick-walled fibres associated with departing leaf traces together with the sclerenchymatous pith and with abundant sclerenchyma fibres in the inner stipe cortex enable assignment to Todea. The stem differs from T. tidwellii—the only other known fossil Todea stem described thus far—mainly in lacking sclerenchyma lining the adaxial concavity of the stipe bundle. Co-occurrence with sterile foliage fragments indicates that the stem may belong to Todea amissa, a species that was initially described based on frond compressions from the same deposits. Our finding corroborates the widely disjunct Gondwanan distribution of Todea across the Southern Hemisphere in the past, and provides an impetus to re-assess genetic divergence between the relictual African and Australasian populations of Todea barbara today in order to resolve the evolutionary history of the group more clearly. Finally, this first report of structurally preserved plant remains from Laguna del Hunco highlights the thus far untapped potential for anatomical preservation in this important fossil lagerstatte.

Ziyang Fauna: A slope facies fossil lagerstätte of Early Ordovician in South China

“Great Ordovician Biodiversification Event” (GOBE) is one of the major biological innovation in Phanerozoic. Trilobite is one of the major taxa in Cambrian and Ordovician. In 1998, Adrain divided the global Ordovician trilobites into two groups, i.e. Ibex Fauna and Whiterock Fauna, and subsequently, the former was subdivided into Ibex I and Ibex II faunas in 2004. The Ordovician radiation of the trilobites was associated with temporal and spatial expansion of the Whiterock Fauna and contraction of the Ibex Fauna. Ibex Fauna is also known as the Cambrian Evolutionary Fauna, which originated at Cambrian, had high diversity and differentiation soon, decline rapidly in Early Ordovician, and went extinct in Late Ordovician. The Ibex I Fauna raised and flourished only in the Early Tremadocian, while Ibex II fauna declined after the Early Ordovician radiation. Whiterock Fauna is also called the Paleozoic Evolutionary Fauna, which appears in Early Ordovician and shows rapidly radiation and high diversification in Middle Ordovician, and then survived the Ordovician Mass Extinction, evolved into Silurian Fauna, some of them might develop and extend to Devonian, Carboniferous and Permian. In 2006, Zhiyi Zhou dubbed the Ordovician trilobite radiation in the South China Block, suggested that the time of onset and the environmental pattern of the Ordovician trilobite radiation may have varied geographically, and the major radiation was likely a long-sustained event that extended through about 25 Ma of the late Early-early Late Ordovician interval, coinciding with the worldwide expansion and domination of the Whiterock Fauna. So the taxa of Zhou’s Ibex Fauna were proportionally dominant over those of Whiterock Fauna. Ziyang fauna, an Early Ordovician fossil lagerstatte is discovered and reported from Ziyang County, Shaanxi Province. It is Floian (the late Early Ordovician) in age based on the occurrences of Tetragraptus approximatus Nicholson. The fossiliferous rocks are blackish-grey mud limestone and calcareous mudstone of possible slope facies in the Yangzte platform. The fauna is dominated by trilobites, accompanied with graptolites, brachiopods, arthropods and some trace fossils. With relatively high taxonomic diversity, the trilobites in this fauna mainly consist of Seleneceme , Niobe , Nileus , Ampyx , Degamella , Borogothus , Geragnostus and Dividuagnostus , etc assgigned to seven families, of them, Asaphidae, Nileidae, Agnostoidea, Peragnostoidea and Alsataspidiae belong to the Ibex Fauna, and Cyclopygidae and Raphiophoridae belong to Whiterock Fauna. Asaphidae and Nileidae are main components of Ibex I Fauna, and Agnostoidea, Peragnostoidea and Alsataspidiae are components of Ibex II Fauna respectively. Quantitatively, Alsataspidiae and Asaphidae account for more than 75% of the total fauna, Ibex I Fauna were predominent over Ibex II Fauna. Other associated fossils include graptolites of Tetragraptus approximatus , Tetragraptus bigsbyi , Tetragraptus quadribrachiatus , Tetragraptus sp., and Paratemnograptus sp., and brachiopods of Tritoechia , Lingulella , etc. The distinctive composition of Ziyang Fauna holds promise for providing insights into the evolution between Ibex and Whiterock faunas in South China.

Taphonomy of fish concentrations from the Upper Jurassic Solnhofen Plattenkalk of Southern Germany

The density of vertebrate fossils on bedding planes is generally very low in the Upper Jurassic plattenkalks forming the Solnhofen fossil Lagerstatte. There are, however, a few bedding planes where large concentrations of the small fis Leptolepides sprattiformis (BLAINVILLE, 1818) occur. The aim of this paper is to analyse and interpret these f sh concentrations from a taphonomic point of view. For this purpose, the taphonomic features of L. sprattiformis concentrations on three large slabs were semi-quantitatively analysed. The concentrations of individuals on bedding planes are explained as recording local mass mortality events caused by tropical storms that, for short intervals, disrupted the pycnocline which separated hypersaline, oxygen-poor to anoxic bottom waters from normal marine surface waters in the Plattenkalk basins. Mass mortality is supported by tetany features such as gaping jaws, hyperextended branchiostegal rays, and splayed f ns, which occur in the majority of the specimens. The generally excellent preservation of the f sh resulted from lack of postmortem f oatation, rapid burial and/or overgrowth by microbial f lms, and quick re-establishment of the pycnocline with inhospitable conditions on the basin floo. The post-mortem concave-arching of the backbones and various displacements of the vertebral column were most likely caused by varying decay resistance of soft tissues and the pressure of decay gases in the body cavities, respectively. The taphonomic analysis of f sh concentrations can provide very detailed palaeoenvironmental information and serves as an independent line of evidence for palaeoenvironmental reconstructions that complements geochemical and sedimentary data.

Ediacaran integrative stratigraphy and timescale of China

Ediacaran successions occur widely in various depositional facies in South China and yield a series of fossil Lagerstatten, providing a complete fossil record for the evolution of marine ecosystems after the terminal Cryogenian global glaciation. Carbonate-dominated Ediacaran successions in shallow water facies in South China record a nearly complete δ 13C profile that may reflect variations of marine carbon isotopic composition during the Ediacaran Period. The Ediacaran fossils and δ 13C profiles from South China permit stratigraphic correlation and subdivision of the Ediacaran strata. Based on biostratigraphic, chemostratigraphic, and geochronometric data from the Ediacaran successions in South China, we propose that the Ediacaran System in China can be subdivided into two series, with three stages in each series. The lower series is characterized by acanthomorphic acritarchs and the upper series by Ediacara-type macrofossils, and the two series are separated by the declining limb of a pronounced δ 13C negative excursion (EN3) in the upper Doushantuo Formation. The basal boundary of Stage 1 is the same as the basal boundary of Ediacaran System, which has been defined at the base of the cap carbonate unit. Stage 2 represents the first radiation of Ediacaran microscopic organisms, with δ 13C feature representing by positive values (EP1). The base of the Stage 2 is placed at the first appearance level of a spiny acritarch species. Stage 3 is characterized by the occurrence of more diverse acritarchs and δ 13C feature EP2, with its basal boundary defined by a δ 13C negative excursion (EN2) occurring in the middle Doushantuo Formation. The basal boundary of Stage 4 is the same as the upper series. Stage 5 is marked by the occurrence of macrfossils of Miaohe biota, and its lower boundary can be placed at the level where δ 13C values transition from positive to negative in MNE, or the first appearance level of macrofossils of the Miaohe biota. Stage 6 is characterized by the occurrences of Ediacara-type Shibantan biota and Gaojiashan biota, with its lower boundary defined by the first appearance level of Conotubus hemiannulatus . The formal establishment of the aforementioned series and stages requires further and more detailed integrative stratigraphic study on the Ediacaran successions in China. Some of the Ediacaran successions in South China have great potential to become global standards in Ediacaran subdivision.

Opening up a window into ecosystems with Ediacara-type organisms: preservation of molecular fossils in the Khatyspyt Lagerstätte (Arctic Siberia)

The Khatyspyt Formation in Arctic Siberia is one of only two carbonate settings with Ediacara-type fossils. As a potential hydrocarbon source rock, it contains abundant molecular fossils that may help to expand our understanding of these ecosystems. Unfortunately, however, the molecular fossil record in geological materials is commonly biased by secondary processes such as thermal maturation, migration of bitumen compounds or surface contamination. In this study, we evaluate the preservation of molecular fossils in a sample from the Khatyspyt Formation and elucidate their paleobiological meaning. Our results reveal that the organic matter is remarkably immature (oil window maturity) and shows little effect of biodegradation. Petrographic observations, exterior/interior experiments, and the similarity between free bitumen, mineral-occluded bitumen, and kerogen pyrolysate point to the syngeneity of the molecular fossils. Abundant hopanes, cyclohexylalkanes, and methyl-branched alkanes indicate a bacterial source of the organic matter, likely including cyanobacteria and anaerobic bacteria. At the same time, a carbonaceous compression fossil on top of the sample and abundant steranes indicate the presence of eukaryotes. The steranes show typical distributions for the Ediacaran (i.e., dominance of stigmastane). Given the exceptional preservation of the body fossils, trace fossils, and molecular fossils, the Khatyspyt Formation can be considered a fossil lagerstatte sensu Seilacher (1970: Begriff und Bedeutung der Fossil-Lagerstatten. Neues Jahrbuch fur Geologie und Palaontologie, Monatshefte: 34–39). The combined analysis of sedimentary facies, paleontology (body, trace, and molecular fossils), and biogeochemistry will provide a more complete understanding of ecosystems with Ediacara-type fossils.

First record of the family Trogossitidae (Insecta, Coleoptera) in the Late Pliocene deposits of Willershausen (Germany)

A new species of the genus Peltis (Coleoptera, Trogossitidae, Peltinae), P. antehercynica sp. nov., is described from the Pliocene lake sediments of the former clay pit of Willershausen (Lower Saxony, Germany). The clearly visible antennae and elytra sculpturing of fossil provide clear morphological information about generic position, and other features, some of them unique in the Peltinae, show that it is an independent new way. In addition, the importance, geology and stratigraphy of the Willershausen Fossil Lagerstatte is briefly discussed.

Diverse, primitive termites (Isoptera: Kalotermitidae,incertae sedis) from the early Miocene of New Zealand

The fauna of termites (Isoptera) preserved in the early Miocene Foulden Maar fossil lagerstatte, Otago, southern New Zealand, is described and figured. Six genera and species, inclusive of Stolotermes kupe Kaulfuss et al. (Stolotermitidae), are now known from Miocene New Zealand; most are attributable to the Kalotermitidae (drywood termites) and one, left as family incertae sedis, has kalotermitid-like traits. The new taxa established are Waipiatatermes matatoka Engel & Kaulfuss gen. et sp. nov., Taieritermes krishnai Engel & Kaulfuss gen. et sp. nov., Otagotermes novazealandicus Engel & Kaulfuss gen. et sp. nov. and Pterotermopsis fouldenica Engel & Kaulfuss gen. et sp. nov. The affinities of the new taxa are discussed, highlighting the composition and uniqueness of the fauna, the absence of Neoisoptera and the possibility that these species were relicts of basal Kalotermitidae.

Dental Eruption Series and Replacement Pattern in Miocene Prosantorhinus (Rhinocerotidae) as Revealed by Macroscopy and X-ray: Implications for Ontogeny and Mortality Profile

Fossil evidence of complete sequences of dental ontogeny in extinct mammals is rare but contains valuable information on the animal’s physiology, life history, and individual age. Here, we analyzed an exceptionally high number of juvenile dentaries at different developmental stages including highly fragile tooth germs of the extinct rhinoceros Prosantorhinus germanicus from the Miocene fossil lagerstatte Sandelzhausen in Germany. We used dental wear stages, eruption stages, and tooth germ development in order to reconstruct the tooth replacement pattern for P. germanicus. The results allow for the distinction of 11 dental eruption stages and document a tooth eruption sequence of (d2, d3), (d1, d4), m1, m2, p2, p3, p4, m3; a pattern identical to that reported for the extant African rhinoceros, Diceros bicornis. Moreover, our findings indicate that P. germanicus falls into the life history category of slow-growing, long-living mammals. The dental eruption stages of the fossil rhinoceros were correlated with data of living rhinoceroses in order to gain insight into the age-at-death distribution of P. germanicus at Sandelzhausen. The juvenile mortality profile of P. germanicus shows a trend of selective mortality at an inferred age range of about 3 months to 3 years. As this age range represents a life phase of increased natural risk of mortality, our findings indicate a gradual accumulation of corpses (attritional fossil assemblage). This result supports the interpretation of a taphocenosis found at the Sandelzhausen fossil site.

Uncovering framboidal pyrite biogenicity using nano-scale CNorg mapping

Framboidal pyrite has been used as a paleo-redox proxy and a biomarker in ancient sediments, but the interpretation of pyrite framboids can be controversial, especially where later overgrowths have obscured primary textures. Here we show how nano-scale chemical mapping of organic carbon and nitrogen (CN org ) can detect relict framboids within Precambrian pyrite grains and determine their formation mechanism. Pyrite grains associated with an Ediacaran fossil Lagerstatte from Newfoundland (ca. 560 Ma) hold significance for our understanding of taphonomy and redox history of the earliest macrofossil assemblages. They show distinct chemical zoning with respect to CN org . Relict framboids are revealed as spheroidal zones within larger pyrite grains, whereby pure pyrite microcrystals are enclosed by a mesh-like matrix of pyrite possessing elevated CN org , replicating observations from framboids growing within modern biofilms. Subsequent pyrite overgrowths also incorporated CN org from biofilms, with concentric CN org zoning showing that the availability of CN org progressively decreased during later pyrite growth. Multiple framboids are commonly cemented together by these overgrowths to form larger grains, with relict framboids only detectable in CN org maps. In situ sulfur isotope data (δ 34 S = ∼−24‰ to −15‰) show that the source of sulfur for the pyrite was also biologically mediated, most likely via a sulfate-reducing microbial metabolism within the biofilms. Relict framboids have significantly smaller diameters than the pyrite grains that enclose them, suggesting that the use of framboid diameters to infer water column paleo-redox conditions should be approached with caution. This work shows that pyrite framboids have formed within organic biofilms for at least 560 m.y., and provides a novel methodology that could readily be extended to search for such biomarkers in older rocks and potentially on other planets.

Fossil treasure house for exploring the Cambrian explosion

Since the 1980s, fossil assemblages of a similar composition and preservation state to the Burgess Shale fauna have been found in Cambrian shales in other parts of Laurentia, for example the Sirius Passet fauna in North Greenland, and in other Cambrian continents, for example the Chengjiang fauna in South China. Such fossil assemblages, termed as Burgess Shale-type fossil Lagerstatten, have long served as fossil treasure houses to explore the Cambrian explosion. In addition to the Chengjiang fauna, more than ten Burgess-Shale-type Lagerstatten are now known from the early to middle Cambrian shales of South China in a succession of stratigraphical horizons [3]. Comparison of such fossiliferous Lagerstatten in a chronological framework enables us to trace the evolutionary changes of biological communities in mud-dominated marine environments. Moreover, comparative studies between a single lineage from different horizons may reveal evolutionary trends in lineages through time. The Xiazhuang Assemblage discovered by Zeng et al. [4] is the latest addition of such wonderful fossil treasure houses. A brief survey shows that the Xiazhaung Assemblage generally resembles the Chengjiang fauna in faunal composition, yielding predominantly soft-bodied fossils, including arthropods, brachiopods, priapulids, lobopods and some problematic taxa, with arthropods being the most dominant group. Specimens illustrated by Zeng et al. [4] comprise a variety of species that are similar or identical to those from the Chengjiang fauna. However, some of the most common species, e.g. Kunmingella douvillei, have not been found in the Xiazhuang Assemblage. The current fossil collection of the Xiazhaung assemblages is rather limited in both number of specimens and species, largely due to constrained excavation. In contrast, 20 years of collecting the Chengjiang fauna at many sites across Eastern Yunnan has yielded more than 200 species and hundreds of thousands of specimens. It is therefore worthwhile to increase the intensity of fossil collection at different localities and sites.

A diverse fossil terrestrial arthropod fauna from New Zealand: evidence from the early Miocene Foulden Maar fossil lagerstätte

Fossil evidence for the evolutionary history of terrestrial arthropods in New Zealand is extremely limited; only six pre-Quaternary insects (Triassic to Eocene) have been recorded previously, none of Miocene age. The Foulden Maar fossil lagerstatte in Otago has now yielded a diverse arthropod assemblage, including members of the Araneae, Plecoptera, Isoptera, Hemiptera, Coleoptera, Hymenoptera, Trichoptera and Diptera. The fauna significantly emends the fossil record for the Southern Hemisphere, provides an unparalleled insight into a 23-million-year-old New Zealand lake/forest palaeoecosystem and allows a first evaluation of arthropod diversity at a time coeval with or shortly after the maximum marine transgression of Zealandia in the late Oligocene. The well-preserved arthropods chiefly represent ground-dwelling taxa of forest floor and leaf litter habitats, mostly from sub-families and genera that are still present in the modern fauna. They provide precisely dated fossil evidence for the antiquity of some of New Zealand's terrestrial arthropods and the first potential time calibrations for phylogenetic studies. The high arthropod diversity at Foulden Maar, together with a subtropical rainforest flora and fossil evidence for complex arthropod–plant interactions, suggests that terrestrial arthropods persisted during the Oligocene marine transgression of Zealandia.

Preliminary note on fossil flowers and inflorescences from the late Oligocene of Enspel (Westerwald, W-Germany)

The present contribution provides a first preliminary overview on flowers and inflorescences which have been discovered in the late Oligocene Fossil–Lagerstatte Enspel. These findings have so far been neglected in palaeobotanical studies on this locality, but several morphologically different types of flowers and inflorescences can be distinguished. Most of these have not yet been determined. The excellent morphological preservation of many of the flowers demonstrates that further careful investigations of these remains may provide important additional information about the diversity of this important palaeoflora and its palaeoenvironment.

Early Jurassic bennettitalean reproductive structures of Romania

The Romanian Early Jurassic (Hettangian–Sinemurian) floras represent a key element of the Eurosinian Province in which the Williamsoniaceae (Bennettitales) are well represented by vegetative remains (leaves, stems, roots) and reproductive structures. Up to the present, Early Jurassic bennettitalean reproductive structures have been found at only two localities in Romania: Anina and Doman. These localities belong to the Resiţa Basin, Getic Nappe, South Carpathians, Romania, with Anina considered to be the best Romanian Early Jurassic locality in terms of diversity and preservation of fossil plants and animals, i.e. a fossil Lagerstatte. This paper deals with all bennettitalean reproductive structures identified to date. These belong to the Steierdorf Formation, Valea Tereziei Member, and are Sinemurian in age. In total, 32 rare hand specimens (compressions and casts) have been studied and the following taxa identified: Williamsonia banatica Krasser, W. latecostata Semaka, Bennetticarpus sp. A and sp. B, Cycadolepis sp., Weltrichia alfredii Krasser, Weltrichia givulescui Popa, 2001, Weltrichia johannae sp. nov., Weltrichia antonii sp. nov., Weltrichia steierdorfensis sp. nov., Weltrichia sp. A and Weltrichia sp. B. The systematic affinities of these taxa are discussed, as well as aspects related to their stratigraphy and palaeocology.

A Lower Cretaceous ichthyosaur graveyard in deep marine slope channel deposits at Torres del Paine National Park, southern Chile

Remnants of ophthalmosaurid ichthyosaurs recently discovered in the vicinity of the Tyndall Glacier in the Torres del Paine National Park of southern Chile are extremely abundant and well preserved. After three field campaigns to the area, a total of 46 articulated and virtually complete ichthyosaur specimens, both adults and juveniles, were tentatively assigned to four different species of Ophthalmosauridae. Preservation is excellent and occasionally includes soft tissue and embryos. The skeletons are associated with ammonites, belemnites, inoceramid bivalves, and fishes as well as numerous plant remains. The enormous concentration of ichthyosaurs is unique for Chile and South America and places the Tyndall locality among the prime fossil Lagerstatten for Early Cretaceous marine reptiles worldwide. The deposit is Early Cretaceous (Valanginian–Hauterivian) in age and forms part of a monotonous bathyal to abyssal sequence of the Late Jurassic to late Early Cretaceous Rocas Verdes back-arc basin. In this region, the Tyndall ichthyosaur population may have profited from cold upwelling currents that caused abundant life at the shelf edge including masses of belemnites and small fish, the preferred diet of ichthyosaurs. The abundance of almost completely articulated ichthyosaur skeletons in the Tyndall area suggests that some animals fell victim to episodic mass-mortality events caused by turbidity currents traveling downslope through a submarine canyon. They lost orientation, drowned, and were dragged into the deep sea by these turbulent high-energy gravity flows. Their bodies ended up in an oxygen-deficient basin environment where they were immediately embedded by the fine turbidite suspension fallout. The Tyndall ichthyosaur locality thus combines characteristics of both concentration and conservation Lagerstatten.

MOLECULAR PRESERVATION OF CENOZOIC CONIFER FOSSIL LAGERSTATTEN FROM BANKS ISLAND, THE CANADIAN ARCTIC

Abstract The molecular preservation of exceptionally preserved conifer needles from middle Miocene and Pliocene deposits on Banks Island, Canada, was investigated using pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS). Solvent-extracted residues from Miocene Larix, Glyptostrobus, and Pinus, Pliocene Picea, and their associated bulk material, yielded abundant polysaccharide pyrolysis products, such as 2-methylfuran, 2-furaldehyde, and levoglucosan, indicating excellent molecular preservation. Comparison of pyrolysates of individual plant taxa and bulk material from the same deposits revealed the dominance of particular plant taxa in these high latitude floras. Comparison with fossil Lagerstatten from Ellesmere Island (late Paleocene) and Axel Heiberg Island (middle Eocene), both in the Canadian Arctic Archipelago, and Clarkia in Idaho, United States (middle Miocene), demonstrated that the quality of molecular preservation of material from Banks Island is similar to that of Axel Heiberg Island and ...

From tree to shining sea: taphonomy of the arboreal lizard Geiseltaliellus maarius from Messel, Germany

Much has been written about the palaeoenvironment of the middle Eocene fossil Lagerstatte of Messel, Germany, and of the taphonomy of the vertebrates found in it, but taphonomic phenomena among the reptiles in this locality are virtually unstudied. The iguanid Geiseltaliellus maarius is the most common lizard species in Messel. We present taphonomic data for this species and analyse it. Specimens of G. maarius can be divided into three preservation classes, one of which is distinguished purely by decompositional phenomena. Most specimens sank quickly to the bottom of Lake Messel after entering it, but one floated for some time prior to emplacement. In theory, overlying pressure should not preclude the accumulation of gases of decay in submerged carcasses. In one specimen, such gases appear to have built up intracoelomically for many weeks, but did not cause the carcass to rise because of overlying water pressure. Eruption of the gases through the oral and cloacal openings, possibly initiated by a coincident turbidity current, scattered the bones of the skull, the pelvic region, and the proximal part of the tail. G. maarius had evolved a form of intervertebral urotomy (pseudoautotomy), which is indicative of arboreal habits. The waxy substance adipocere, formed after breakdown of fat, has been neglected in discussions of taphonomy, but may constitute an important factor in stabilising carcasses and enabling three-dimensional preservation before diagensis.

Taphonomy of the earliest Cambrian linguliform brachiopods

The Early Cambrian Burgess Shale-type fossil Lagerstatten of Yunnan Province (Chengjiang; Guanshan) are crucial in understanding the Cambrian bioradiation. Brachiopods are applied here as a critical model phylum to analyze the taphonomy of Yunnan fossil Lagerstatten, because shell and tissue composition of modern brachiopods can be compared with exceptionally preserved Cambrian remains. Systematic elemental mapping and energy-dispersive X-ray analyses have been carried out to study fossil brachiopods and their matrix from Cambrian Stages 3–4 and modern linguliform brachiopods from several geographical regions in order to evaluate the detailed structure of the shells and the biological and environmental influences on shell composition. Analyses of earliest Cambrian fossils encompassing the complete spectrum of weathering stages show a primary organo-phosphatic brachiopod shell, visible in unweathered specimens, and a successive dissolution and replacement of the shell during weathering, observable in speci...

A new link between Orsten-type assemblages and the Burgess Shale—a Marrella-like arthropod from the Cambrian of Australia

An isolated exopod in uncompressed three-dimensional “Orsten”-type preservation from the Cambrian of Australia represents a new species of Marrellomorpha, Austromarrella klausmuelleri gen. et sp. nov. The exopod is composed of at least 17 annuli. Each of the proximal annuli carries a pair of lamellae: one lamella on the lateral side and one on the median side. The distal annuli bear stout spines in the corresponding position instead of lamellae, most likely representing early ontogenetic equivalents of the lamellae. The new find extends the geographical range of the taxon Marrellomorpha. Additionally, it offers a partial view into marrellomorph ontogeny. The occurrence of a marrellomorph fragment in “Orsten”-type preservation provides new palaeo-ecological insights into the possible connections between the “Orsten” biotas and other fossil Lagerstatten. Finding such connections is necessary for understanding the complex ecosystems of early Palaeozoic times.

FEATHERS OF THE INGERSOLL SHALE, EUTAW FORMATION (UPPER CRETACEOUS), EASTERN ALABAMA: THE LARGEST COLLECTION OF FEATHERS FROM NORTH AMERICAN MESOZOIC ROCKS

The Ingersoll shale (Santonian) is a small mudstone lens in eastern Alabama, interpreted as an abandoned tidal-channel fill that accumulated rapidly within the lower reaches of a bayhead delta. The diverse biota found in this fossil Lagerstatte includes 14 individual feather specimens, the largest collection known from the Mesozoic of North America. Occurring separately throughout nearly the entire thickness of the clay lens and with a range of sizes and morphologies, the feathers most likely represent a number of theropod species. Based on known taxa in the region, the largest specimen (16.5 cm) may be a rectrix (tail feather) from a dromaeosaurid dinosaur or from a hesperornithid. Smaller feathers may have belonged to a range of shore birds. The best-preserved specimens were found in the finest grained intervals. SEM examination reveals very well preserved microstructure consisting of carbonized rod-shaped bodies ∼1 µm in length, preserved in three dimensions and solid internally. Although identical in size and shape to modern feather-degrading bacilliform bacteria and displaying some bacteria-like features, their alignment along the axis of feather structures indicates that they are more likely the fossil remains of melanosomes, melanin bodies used for color production during life. No three-dimensional arrays or patterned differences of morphotypes have been seen thus far; almost all elements are elongate (apparently eumelanin). Inferred colors for four of the feathers, based on differences in melanosome morphologies, range from gray and brownish gray to black. Whereas the majority of feather-bearing deposits represent inland lakes, the estuarine setting adds a view of coastal feathered theropods preserved in detail by rapid deposition of fine-grained sediment.

CAMBRIAN ORSTEN LAGERSTATTE FROM THE ALUM SHALE FORMATION: FECAL PELLETS AS A PROBABLE SOURCE OF PHOSPHORUS PRESERVATION

The Furongian Orsten-type fossil Lagerstatte in the Alum Shale Formation of Sweden is an extraordinary deposit known for its detailed, three-dimensional preservation of the soft parts of small animal carcasses which have been replaced by calcium phosphate and occur in organic-rich nodular limestone. The exact cause and mechanism of this unusual fossil preservation, however, particularly the source of phosphorus, which plays a key role, remains unknown. Detailed observation in the Agnostus pisiformis Zone in the Backeborg section (Kinnekulle district) reveals that the phosphatocopine crustaceans showing soft-part preservation occur only in a few thin (<3 cm) layers containing abundant fecal pellets (pellet beds). Development of cross lamination suggests that the pellet beds were formed by low density sediment-gravity flow. Orsten-type preservation has been attributed to high phosphate levels in global marine waters during the Cambrian period; however, wavelength-dispersive X-ray and X-ray diffractometry analyses reveal that the Orsten limestones and surrounding shale were generally poor in phosphorus, which was mostly concentrated in the fecal pellets. The small animal carcasses preserved in such deposits were phosphatized during early diagenesis owing to the high local phosphorus levels of the accumulated fecal pellets. Searches for such cesspool-type preservation may yield further discoveries of Orsten-type fossil Lagerstatten in other strata of various ages.