Fossil mesostigmatid mites (Mesostigmata: Gamasina, Microgyniina, Uropodina), associated with longhorn beetles (Coleoptera: Cerambycidae) in Baltic amber

Fossil mesostigmatid mites are extremely rare. Inclusions assignable to the tortoise mites (Mesostigmata, Uropodina) are described here for the first time from Eocene (ca. 44–49 Ma) Baltic amber. This is the oldest record of Uropodina and documents the first unequivocal amber examples potentially assignable to the extant genus Uroobovella Berlese, 1903 (Uropodoidea: Urodinychidae). Further mites in the same amber pieces are tentatively assigned to Microgynioidea (Microgyniina) and Ascidae (Gamasina), both potentially representing the oldest records of their respective superfamily and family groups. This new material also preserves behavioural ecology in the form of phoretic deutonymphs attached to their carriers via a characteristic anal pedicel. These deutonymphs in amber are intimately associated with longhorn beetles (Coleoptera: Cerambycidae), probably belonging to the extinct species Nothorhina granulicollis Zang, 1905. Modern uropodines have been recorded phoretic on species belonging to several beetle families, including records of living Uroobovella spp. occurring on longhorn beetles. Through these amber inclusions, a uropodine–cerambycid association can now be dated back to at least the Eocene.     

The oldest haplogyne spider (Araneae: Plectreuridae), from the Middle Jurassic of China

New fossil spiders (Arachnida: Araneae) from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China are described as Eoplectreurys gertschi gen. et sp. nov. and referred to the modern haplogyne family Plectreuridae. This small family is restricted to southwestern USA, Mexico, and the adjacent Caribbean area today and hitherto has only a sparse Cenozoic fossil record. The morphology of Eoplectreurys is remarkably similar to modern forms and thus demonstrates great evolutionary conservatism. This new discovery not only extends the fossil record of the family by at least 120 Ma to the Middle Jurassic but also supports the hypothesis of a different distribution of the family in the past than today and subsequent extinction over much of its former range.     

Brainy stuff of long-gone dogs: a reappraisal of the supposed Canis endocranial cast from the Pliocene of Poland

The pre-Quaternary fossil record of Canis in the Old World is scarce, and the first appearance of this genus in Europe remains an enigma. Amongst the oldest fossils assigned to this genus, there is a natural cast of the brain (endocast) collected in W??e 1, Poland, from Pliocene deposits dated between 3.3 and 4.0 Ma. We reexamined this specimen and found that it differs from the brain of Canis in having its region medial to the coronal sulcus heart-shaped in dorsal view, its region rostral to the presylvian sulcus shorter and less constricted laterally, and its cerebellum less overlapped by the cerebrum and lacking a lateral twist of the posterior vermis. We identified this fossil, as well as another fossil canid endocast from W??e 1, as representing the raccoon dog genus Nyctereutes. The previously reported presence of Canis in W??e 1 is therefore not confirmed. Specifically, both endocasts can be referred to N. donnezani because this is the only species of Nyctereutes that has been recognised in this locality on the basis of craniomandibular and dental fossils. Our study represents a taxonomic application of comparative neuroanatomical and palaeoneurological data, an approach that may become increasingly useful with the growing knowledge of the endocranial morphology of fossil mammals.     

A new fossil thryonomyid from the Late Miocene of the United Arab Emirates and the origin of African cane rats

Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than “Thryonomys” asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6–8 Ma).     

Fossil evidence for the early ant evolution

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution.     

The oldest micropepline beetle from Cretaceous Burmese amber and its phylogenetic implications (Coleoptera: Staphylinidae)

The staphylinid subfamily Micropeplinae includes small strongly sclerotized beetles with truncate elytra leaving the most part of abdomen exposed. Fossil micropeplines are rare and confined to Cenozoic representatives of extant genera. Here, we describe the oldest micropepline, Protopeplus cretaceus gen. and sp. n., from the Upper Cretaceous Burmese amber. Fluorescence microscope and confocal laser scanning microscopy (CLSM) were both used to reveal diagnostic features of Micropeplinae and some primitive traits that place Protopeplus very basally within Micropeplinae.     

Biomolecules preserved in ca. 168 million year old fossil conifer wood

Biomarkers are widely known to occur in the fossil record, but the unaltered biomolecules are rarely reported from sediments older than Paleogene. Polar terpenoids, the natural products most resistant to degradation processes, were reported mainly from the Tertiary conifers, and the oldest known are Cretaceous in age. In this paper, we report the occurrence of relatively high concentrations of ferruginol derivatives and other polar diterpenoids, as well as their diagenetic products, in a conifer wood Protopodocarpoxylon from the Middle Jurassic of Poland. Thus, the natural product terpenoids reported in this paper are definitely the oldest polar biomolecules detected in geological samples. The extracted phenolic abietanes like ferruginol and its derivatives (6,7-dehydroferruginol, sugiol, 11,14-dioxopisiferic acid) are produced only by distinct conifer families (Cupressaceae s. l., Podocarpaceae and Araucariaceae), to which Protopodocarpoxylon could belong based on anatomical characteristics. Therefore, the natural product terpenoids are of great advantage in systematics of fossil plant remains older than Paleogene and lacking suitable anatomical preservation.     

First complete sauropod dinosaur skull from the Cretaceous of the Americas and the evolution of sauropod dentition

Sauropod dinosaur bones are common in Mesozoic terrestrial sediments, but sauropod skulls are exceedingly rare—cranial materials are known for less than one third of sauropod genera and even fewer are known from complete skulls. Here we describe the first complete sauropod skull from the Cretaceous of the Americas, Abydosaurus mcintoshi, n. gen., n. sp., known from 104.46 ± 0.95 Ma (megannum) sediments from Dinosaur National Monument, USA. Abydosaurus shares close ancestry with Brachiosaurus, which appeared in the fossil record ca. 45 million years earlier and had substantially broader teeth. A survey of tooth shape in sauropodomorphs demonstrates that sauropods evolved broad crowns during the Early Jurassic but did not evolve narrow crowns until the Late Jurassic, when they occupied their greatest range of crown breadths. During the Cretaceous, brachiosaurids and other lineages independently underwent a marked diminution in tooth breadth, and before the latest Cretaceous broad-crowned sauropods were extinct on all continental landmasses. Differential survival and diversification of narrow-crowned sauropods in the Late Cretaceous appears to be a directed trend that was not correlated with changes in plant diversity or abundance, but may signal a shift towards elevated tooth replacement rates and high-wear dentition. Sauropods lacked many of the complex herbivorous adaptations present within contemporaneous ornithischian herbivores, such as beaks, cheeks, kinesis, and heterodonty. The spartan design of sauropod skulls may be related to their remarkably small size—sauropod skulls account for only 1/200th of total body volume compared to 1/30th body volume in ornithopod dinosaurs.     

Europe's last Mesozoic bird

Birds known from more than isolated skeletal elements are rare in the fossil record, especially from the European Mesozoic. This paucity has hindered interpretations of avian evolution immediately prior to, and in the aftermath of, the Cretaceous-Tertiary (K-T) extinction event. We report on a specimen of a large ornithurine bird (closely related to Ichthyornis) from the uppermost Cretaceous (Maastricht Formation) of Belgium. This is the first record of a bird from these historic strata and the only phylogenetically informative ornithurine to be recovered from the Mesozoic of Europe. Because this new specimen was collected from 40 m below the K-T boundary (approximate age of 65.8 Ma), it is also the youngest non-neornithine (=non-modern) bird known from anywhere in the world.     

The first multituberculate mammal from India

Mesozoic deposits of the former Gondwanaland are depauperate in early mammals, in general, and multituberculate mammals, in particular. Until now, the oldest multituberculate mammals known from the Gondwanan continents come from the Early Cretaceous of Morocco, NW Africa. Here, we report the presence of a new multituberculate mammal, Indobaatar zofiae gen. et sp. nov., from the Lower/Middle Jurassic Kota Formation, Pranhita-Godavari valley in peninsular India. This is the first record of a multituberculate from the Mesozoic rocks of India and possibly predates the oldest known multituberculates from Gondwanan continents. The new specimen, representing an upper premolar (P⁴), compares well with the upper premolar morphology of Eobaatariinae multituberculates known from the Early Cretaceous of Mongolia, China, England, and Spain. Together with the recent findings of cimolodontan multituberculates from the Early Cretaceous of Australia and Late Cretaceous of South America, the new discovery indicates a wide temporal and spatial distribution for multituberculate mammals in the former Gondwanaland.     

Harvestmen (Arachnida: Opiliones) from the Middle Jurassic of China

Harvestmen (Arachnida: Opiliones) are familiar animals in most terrestrial habitats but are rare as fossils, with only a handful of species known from each of the Palaeozoic, Mesozoic, and Cenozoic eras. Fossil harvestmen from Middle Jurassic (ca. 165 Ma) strata of Daohugou, Inner Mongolia, China, are described as Mesobunus martensi gen. et sp. nov. and Daohugopilio sheari gen. et sp. nov.; the two genera differ primarily in the relative length of their legs and details of the pedipalps. Jurassic arachnids are extremely rare and these fossils represent the first Jurassic, and only the fourth Mesozoic, record of Opiliones. These remarkably well-preserved and modern-looking fossils are assigned to the Eupnoi, whereby M. martensi demonstrably belongs in Sclerosomatidae. It thus represents the oldest record of a modern harvestman family and implies a high degree of evolutionary stasis among one of the most widespread and abundant groups of long-legged, round-bodied harvestmen.     

Earliest zygodactyl bird feet: evidence from Early Cretaceous roadrunner-like tracks

Fossil footprints are important in understanding Cretaceous avian diversity because they constitute evidence of paleodiversity and paleoecology that is not always apparent from skeletal remains. Early Cretaceous bird tracks have demonstrated the existence of wading birds in East Asia, but some pedal morphotypes, such as zygodactyly, common in modern and earlier Cenozoic birds (Neornithes) were unknown in the Cretaceous. We, herein, discuss the implications of a recently reported, Early Cretaceous (120–110 million years old) trackway of a large, zygodactyl bird from China that predates skeletal evidence of this foot morphology by at least 50 million years and includes the only known fossil zygodactyl footprints. The tracks demonstrate the existence of a Cretaceous bird not currently represented in the body fossil record that occupied a roadrunner (Geococcyx)-like niche, indicating a previously unknown degree of Cretaceous avian morphological and behavioral diversity that presaged later Cenozoic patterns. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

When xenarthrans had enamel: insights on the evolution of their hypsodonty and paleontological support for independent evolution in armadillos

All xenarthrans known to date are characterized by having permanent teeth that are both high crowned and open rooted, i.e., euhypsodont, and with a type of hypsodonty different from that of the rest of Placentalia: dentine hypsodonty. Also, most xenarthrans lack enamel; however, its presence has been reported in the fossil armadillo Utaetus buccatus and in living Dasypus. Considering the divergence of Xenarthra from other eutherians that possessed enameled teeth, the absence of enamel is a derived character. Diverse specializations are known in the dentition of xenarthrans, but the primitive pattern of their teeth and dentitions is still unknown. Here, we describe the mandible and teeth of a fossil armadillo, Astegotherium dichotomus (Astegotheriini, Dasypodidae), from the early Middle Eocene of Argentine Patagonia, with teeth showing both true enamel and closed roots. It is the oldest xenarthran with mandibular remains exhibiting protohypsodonty and is therefore likely representative of ancestral cingulates and xenarthrans generally. Astegotherium supports a recent hypothesis based on molecular data that enamel loss occurred independently not only within xenarthrans but also within dasypodid armadillos.     

Reconstructing the anatomy of the 42-million-year-old fossil †Mengea tertiaria (Insecta, Strepsiptera)

Fossilization in amber is unique in preserving specimens with microscopic fidelity; however, arthropod inclusions are rarely examined beyond the exoskeleton as this requires destructive sampling when traditional techniques are used. We report the first complete, digital 3D, non-destructive reconstruction of the anatomy of an insect fossil, a specimen of †Mengea tertiaria embedded in a 42-Ma Baltic amber. This was made possible using Synchrotron μ-CT. The species belongs to the stem group of the phylogenetically enigmatic and extremely specialized Strepsiptera. Most internal structures of the fossil are preserved, but small parts of the lumen had decayed due to incomplete infiltration of the resin. Data on internal organs provided additional information for resolving phylogenetic relationships. A sister group relationship between †Mengea and all extant lineages of the group was confirmed with characters previously not accessible. The newly gained information also yielded some insights in the biology of †Mengea and the early evolutionary history of Strepsiptera. The technique has a tremendous potential for a more accurate interpretation of diverse fossil arthropods preserved in ambers from 130 Ma to the present.     

Numerical dating of the Eckfeld maar fossil site, Eifel, Germany: a calibration mark for the Eocene time scale

 Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian. In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By ⁴⁰Ar/³⁹Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has been established. The Eckfeld basalt inverse isochron date of 44.3±0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary at 44 Ma and, together with the 1995 time scale of Berggren et al., a time span ranging from 49 to 44 Ma for the Geiseltalian and from 44 to 37 Ma for the Robiacian, respectively. Additional ⁴⁰Ar/³⁹Ar dating on a genetically related basalt occurrence close to the maar confirms a period of volcanism of ca. 0.6 m.y. in the Eckfeld area, matching the oldest Eocene volcanic activity of the Hocheifel volcanic field. Received: 27 December 1999 / Accepted in revised form: 6 April 2000     

A gravid lizard from the Cretaceous of China and the early history of squamate viviparity

Although viviparity is most often associated with mammals, roughly one fifth of extant squamate reptiles give birth to live young. Phylogenetic analyses indicate that the trait evolved more than 100 times within Squamata, a frequency greater than that of all other vertebrate clades combined. However, there is debate as to the antiquity of the trait and, until now, the only direct fossil evidence of squamate viviparity was in Late Cretaceous mosasauroids, specialised marine lizards without modern equivalents. Here, we document viviparity in a specimen of a more generalised lizard, Yabeinosaurus, from the Early Cretaceous of China. The gravid female contains more than 15 young at a level of skeletal development corresponding to that of late embryos of living viviparous lizards. This specimen documents the first occurrence of viviparity in a fossil reptile that was largely terrestrial in life, and extends the temporal distribution of the trait in squamates by at least 30 Ma. As Yabeinosaurus occupies a relatively basal position within crown-group squamates, it suggests that the anatomical and physiological preconditions for viviparity arose early within Squamata.     

Volcanic mercury in Pinus canariensis

Mercury (Hg) is a toxic element that is emitted to the atmosphere by both human activities and natural processes. Volcanic emissions are considered a natural source of mercury in the environment. In some cases, tree ring records taken close to volcanoes and their relation to volcanic activity over time are contradictory. In 1949, the Hoyo Negro volcano (La Palma-Canary Islands) produced significant pyroclastic flows that damaged the nearby stand of Pinus canariensis. Recently, 60 years after the eruption, we assessed mercury concentrations in the stem of a pine which survived volcano formation, located at a distance of 50 m from the crater. We show that Hg content in a wound caused by pyroclastic impacts (22.3 μg kg^?1) is an order of magnitude higher than the Hg concentrations measured in the xylem before and after the eruption (2.3 μg kg^?1). Thus, mercury emissions originating from the eruption remained only as a mark—in pyroclastic wounds—and can be considered a sporadic and very high mercury input that did not affect the overall Hg input in the xylem. In addition, mercury contents recorded in the phloem (9.5 μg kg^?1) and bark (6.0 μg kg^?1) suggest that mercury shifts towards non-living tissues of the pine, an aspect that can be related to detoxification in volcanism-adapted species.     

Cretaceous choristoderan reptiles gave birth to live young

Viviparity (giving birth to live young) in fossil reptiles has been known only in a few marine groups: ichthyosaurs, pachypleurosaurs, and mosasaurs. Here, we report a pregnant specimen of the Early Cretaceous Hyphalosaurus baitaigouensis, a species of Choristodera, a diapsid group known from unequivocal fossil remains from the Middle Jurassic to the early Miocene (about 165 to 20 million years ago). This specimen provides the first evidence of viviparity in choristoderan reptiles and is also the sole record of viviparity in fossil reptiles which lived in freshwater ecosystems. This exquisitely preserved specimen contains up to 18 embryos arranged in pairs. Size comparison with small free-living individuals and the straight posture of the posterior-most pair suggest that those embryos were at term and had probably reached parturition. The posterior-most embryo on the left side has the head positioned toward the rear, contrary to normal position, suggesting a complication that may have contributed to the mother’s death. Viviparity would certainly have freed species of Hyphalosaurus from the need to return to land to deposit eggs; taking this advantage, they would have avoided intense competition with contemporaneous terrestrial carnivores such as dinosaurs.