An intertidal balanomorph Hexaminius venerai sp. nov. (Austrobalanidae) colonizing a log of Podocarpoxylon from the La Meseta Formation (Eocene), Seymour Island,Antarctica: a glimpse of Antarctic antiquity

Abstract

The sessile barnacle Hexaminius venerai sp. nov. (Tetraclitoidea: Austrobalanidae) is described from the middle Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula. Hexaminius venerai sp. nov. is the earliest known record of the genus in the Antarctic, the first occurrence of Hexaminius from outside Australian waters and the first record of a fossil cirripede attached to the substrate from the Antarctic. Exceptional preservation of more than 200 specimens, some of which retain opercula within the shell, is discussed. In life, the cirripedes were attached to a tree trunk tentatively identified as Podocarpoxylon, a South Hemisphere conifer. Hexaminius venerai sp. nov. is a survivor of an early phase in balanid radiation, prior to the development of strong radially-interlocked parietes.https://zoobank.org/urn:lsid:zoobank.org:pub:EAA2EB5C-BC57-41FA-93A0-046AF5FD59EB     

Fossil penguin (Aves: Sphenisciformes) cranial material from the Eocene of Seymour Island (Antarctica)

Our knowledge of the cranial morphology of early penguins remains poor, particularly for Paleogene taxa. This paper describes a partial penguin skull and additional isolated cranial elements from the Eocene La Meseta Formation of Seymour Island, Antarctica. These specimens cannot be assigned to named taxa at present, but there is a strong possibility they belong to La Meseta penguins known only from postcranial elements. The skull shares extensive dorsal development of the temporal fossae with extant and fossil Spheniscus and the fossil penguins Paraptenodytes and Marplesornis, indicating the adductor complex was powerful in early penguins. Partial mandibles belonging to a much larger penguin are similar to Paraptenodytes and differ from all living penguins in the lack of a hooked medial process of the articular and the presence of a foramen anterior to the mandibular cotyles. Given the rarity of penguin cranial remains, these specimens provide important new insight into early penguin evolution.     

The oldest mammals from Antarctica,early Eocene of the La Meseta Formation,Seymour Island

New fossil mammals found at the base of Acantilados II Allomember of the La Meseta Formation, from the early Eocene (Ypresian) of Seymour Island, represent the oldest evidence of this group in Antarctica. Two specimens are here described; the first belongs to a talonid portion of a lower right molar assigned to the sparnotheriodontid litoptern Notiolofos sp. cf. N. arquinotiensis. Sparnotheriodontid were medium‐ to large‐sized ungulates, with a wide distribution in the Eocene of South America and Antarctica. The second specimen is an intermediate phalanx referred to an indeterminate Eutheria, probably a South American native ungulate. These Antarctic findings in sediments of 55.3 Ma query the minimum age needed for terrestrial mammals to spread from South America to Antarctica, which should have occurred before the final break‐up of Gondwana. This event involves the disappearance of the land bridge formed by the Weddellian Isthmus, which connected West Antarctica and southern South America from the Late Cretaceous until sometime in the earliest Palaeogene.     

Fossilized spermatozoa preserved in a 50-Myr-old annelid cocoon from Antarctica

The origin and evolution of clitellate annelids—earthworms, leeches and their relatives—is poorly understood, partly because body fossils of these delicate organisms are exceedingly rare. The distinctive egg cases (cocoons) of Clitellata, however, are relatively common in the fossil record, although their potential for phylogenetic studies has remained largely unexplored. Here, we report the remarkable discovery of fossilized spermatozoa preserved within the secreted wall layers of a 50-Myr-old clitellate cocoon from Antarctica, representing the oldest fossil animal sperm yet known. Sperm characters are highly informative for the classification of extant Annelida. The Antarctic fossil spermatozoa have several features that point to affinities with the peculiar, leech-like ‘crayfish worms'' (Branchiobdellida). We anticipate that systematic surveys of cocoon fossils coupled with advances in non-destructive analytical methods may open a new window into the evolution of minute, soft-bodied life forms that are otherwise only rarely observed in the fossil record.     

Palaeeudyptes klekowskii, the best-preserved penguin skeleton from the Eocene–Oligocene of Antarctica: Taxonomic and evolutionary remarks

A new fossil penguin skeleton from the La Meseta Formation collected at the locality DPV 13/84 (Seymour Island, Antarctic Peninsula) from the crinoid horizon located 40 m above the base of the 145 m-thick Submeseta Allomember (Late Eocene–Early Oligocene?) is described. The specimen is assigned to the species Palaeeudyptes klekowskii Myrcha, Tatur and del Valle, 1990; it is the most complete penguin skeleton ever recovered from Antarctica. Discoveries like this one are significant for the study of the anatomy and evolution of penguins, in particular regarding the Antarctic species included in the genus Palaeeudyptes Huxley, 1859. P. klekowskii closely resembles its smaller congeneric species P. gunnari ( Wiman, 1905), with only the relative concavity of the margo medialis distinguishing the tarsometatarsi of both taxa. However, the results of a geometric morphometric analysis show some intra- and inter-specific variations, making possible the systematic assignment of the majority of the specimens. Size variation is congruent with the presence of two different species.     

Skates and rays (Elasmobranchii,Batomorphii) from the Eocene La Meseta and Submeseta formations,Seymour Island,Antarctica

Abstract

Eocene deposits of the famous La Meseta Formation of Seymour Island, Antarctic Peninsula, yielded the most diverse Paleogene fossil elasmobranch association of the Southern Hemisphere. In this assemblage, sharks clearly dominate the fauna, whereas batoids are very rare components. Herein, we describe two new taxa of cold water tolerant skates, Marambioraja leiostemma gen. et sp. nov., and Mesetaraja maleficapelli gen. et sp. nov., two new species of the genus Raja, Raja amphitrita sp. nov. and Raja manitaria sp. nov., as well as remains of warm water adapted myliobatiforms. It is, however, not possible to unambiguously assign these remains either to Myliobatidae or Rhinopteridae, or to any specific genus. Previously reported remains of Raja/Bathyraja sp. are assigned to the new described species Raja manitaria sp. nov. The biogeographic distribution of extant and extinct rays and skates clearly shows that both groups are more widely distributed today than in the past, and additionally seem to have been more diverse in the Northern than the Southern Hemisphere. The occurrence, albeit rare of isolated teeth of skates (Rajidae) and rays (Myliobatidae) in the La Meseta Formation representes a minimum age constraint for their first appearance in the Southern Ocean.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:E507D86C-FFEC-4047-A337-AE77606BB1A6     

Eocene Bird and Mammal Tracks from the Karaj Formation,Tarom Mountains,Northwestern Iran

A long continuous trackway of a shorebird (cf. Charadriipeda) and a suite of possible Pantodonta (?Corophydon) or Dinocerata tracks are reported from the Eocene Karaj Formation. Fossil footprints are still rare in Iran, described only from two Jurassic and three Tertiary sites. Thus the current record, the third in the Teritary, adds to a sparse record and increases the diversity of known track types.     

Cyclocarya cf. paliurus (Batal.) Iljinskaja (Juglandaceae) from the Hunchun Formation (Eocene), Jilin Province, China

The leaflet architecture of Cyclocarya cf. paliurus (Batal.) Iljinskaja from the Hunchun Formation (Middle Eocene) shows similarity to that of modern C. paliurus (Batal.) Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records,such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the Eocene period.     

Cyclocarya cf. paliurus （Batal.） Iljinskaja （Juglandaceae） from the Hunchun Formation （Eocene）, Jilin Province, China

The leaflet architecture of Cyclocarya cf. paliurus （Batal.） Iljinskaja from the Hunchun Formation （Middle Eocene） shows similarity to that of modem C. paliurus （Batal.） Iljinskaja and the specimen is the oldest fossil record in Europe and Asia. The distributions of C. cf. paliurus and other fossil records, such as Glyptostrobus, Metasequoia, Nyssa, and Liquidambar, in Hunchun flora show that it would have been a warmer-temperature to subtropical climate in Hunchun District during the Eocene period.     

Palaeoskapha sichuanensis gen. et sp. nov. (Menispermaceae) from the Eocene Relu Formation in western Sichuan, West China

Palaeoskapha sichuanensis gen. et sp. nov. of Menispermaceae is described here for the first time based on a well preserved fossil fruit. The specimen was found in the Relu Formation of western Sichuan, West China. The specimen, straight, boat-shaped endocarp with large ventral condyle, clearly belongs to the tribe Tinosporeae. The wide aperture of the double condyle, combined with a whole shape not deeply invaginated, indicates a genus different from what was already known to science for this tribe. This fossil widens the distribution of the tribe during Eocene from North America and Europe to Asia, where it was formerly unknown.     

Anatomy of the bony pelvis of a relatively large-bodied strepsirrhine primate from the late middle Eocene Pondaung Formation (central Myanmar)

Recent survey of the fossiliferous variegated mudstones of the PK1 locality (Sabapondaung) in the late middle Eocene Pondaung Formation (central Myanmar) has led to the recovery of a partial right innominate of a relatively large-bodied primate. Given its size and provenance, this bone probably belongs to the same individual represented by the NMMP 20 primate partial skeleton described previously from the same locality. The new fossil, which preserves the region around the acetabulum and the adjacent part of the ilium, clearly exhibits strepsirrhine rather than anthropoid affinities. This addition to our knowledge of the NMMP 20 partial skeleton allows us to reassess the different locomotor interpretations that have been proposed for this specimen. Aspects of pelvic morphology suggest that the NMMP 20 partial skeleton documents a primate that probably engaged in active arboreal quadrupedalism similar to that practiced by medium-sized Malagasy lemurids rather than lorislike slow moving and climbing. Given the conflicting phylogenetic signals provided by NMMP 39 (a talus showing anthropoid affinities) and NMMP 20 (a partial skeleton bearing adapiform affinities), it appears that two higher-level taxonomic groups of relatively large-bodied primates are documented in the Pondaung Formation. The recent discovery of two taxa of sivaladapid adapiforms from the Pondaung Formation indicates that the assumption that the NMMP 20 partial skeleton belongs to an amphipithecid can no longer be sustained. Instead, this specimen apparently documents a third large-bodied sivaladapid species in the Pondaung Formation.     

Lunulichnus Tuberosus Ichnogen. and Ichnosp. Nov. from the Early Eocene Wasatch Formation,Fossil Butte National Monument,Wyoming: An Arthropod-Constructed Trace Fossil Associated with Alluvial Firmgrounds

A new trace fossil, Lunulichnus tuberosus, is described from fluvial deposits of the Wasatch Formation (early Eocene) at Fossil Butte National Monument, southwestern Wyoming, USA. L. tuberosus are straight, vertical to obliquely oriented, unlined cylindrical burrows with pronounced crescent-shaped wall sculptings. In situ examples of these trace fossils are most commonly preserved as sand-filled casts emanating from the erosional bases of fluvial channel sandstone bodies into underlying floodplain mudstone/siltstone beds. L. tuberosus is interpreted as the dwelling trace of a stream-dwelling decapod crustacean. Excellent preservation of fine detail, particularly their diagnostic crescent-shaped wall sculptings, support the hypothesis that L. tuberosus were excavated in firm substrata subjacent to fluvial erosional surfaces. As such, they are interpreted as constituents of alluvial Glossifungites trace fossil assemblages.     

Early Eocene macroflora and associated palynofossils from the Cambay Shale Formation,western India: Phytogeographic and palaeoclimatic implications

A diverse assemblage of plant macrofossils and the associated representative palynofloral elements are documented from the early Eocene subsurface beds of the Cambay Shale Formation exposed in an open cast lignite mine at Vastan Village in the Surat District, western India. The Vastan mine succession is cyclic, each cycle representing a transgressive burial event terminating in the low energy lagoonal conditions. The higher energy cycle begins with sandy lenses having rich biotic remains, followed by mudstones and molluscan shell beds and ends with lignite seams. The dominantly muddy facies and the associated biota demonstrate predominantly low energy near shore or coastal plain depositional setting with conditions varying from dominantly marine (shallow) through brackish to fresh water. The Vastan mine is a well dated fossil locality with a rich and diverse biota of mammals, birds, snakes, lizards, fish, insects, molluscs, foraminifers, dinoflagellates, and plants. The plants comprise leaf and fruit impressions, seeds, fruits, wood fragments, mangrove rooting structures, fungal thalli and spores, pteridophytic spores, and angiosperm pollen grains. Thirteen macrofossil species, including several morphotaxa, are represented by the families Calophyllaceae, Rutaceae, Anacardiaceae, Rubiaceae, Combretaceae, Lythraceae, Sapindaceae, Malvaceae, and Ebenaceae. The palynological assemblage representing fourteen taxa includes the new species, Notothyrites undulatus, Callimothallus semicircularis, and Carallioipollenites integerrimoides. Habitat and distribution of modern taxa comparable with the fossil assemblage from Vastan suggest a terrestrial lowland environment. The macrofossil taxa are indicative of mesophytic, mixed forest growing under tropical to subtropical climate with sufficient humidity. The occurrence of dipterocarp elements along with taxa such as Swintonia, Pterospermum and Diospyros, etc. seems to suggest the presence of a tropical rain forest in the vicinity of Vastan.     

A well‐preserved ‘charadriiform‐like’ fossil bird from the Early Eocene Fur Formation of Denmark

Abstract: We describe a new, exceptionally well‐preserved fossil bird recovered from marine deposits of the Early Eocene Fur Formation of Denmark. Morsoravis sedilis gen. et sp. nov. is known by a single specimen that consists of a three‐dimensional skull, vertebral column, ribs, pelvis, and left hindlimb and associated parts of the right hindlimb. Comparisons based on overall morphology and particularly characters of the skull, vertebrae and pelvis indicate that the new specimen is morphologically similar to charadriiform birds (the shorebirds and relatives). This similarity is also expressed by a phylogenetic analysis of higher neornithine (modern birds) taxa, which supports a close relationship between the new fossil and modern charadriiforms. The morphology of the hindlimbs, in particular, shows that the new fossil corresponds to a new taxon that is distinguishable from modern charadriiform clades. One interesting aspect of its morphology is the presence of hindlimb specializations that are most commonly found among perching birds – these suggest that ecologically the new Danish fossil bird may have differed from the wading habits typical of most charadriiforms.     

Stratigraphic interpretation of the Kulu Formation (Early Miocene, Rusinga Island, Kenya) and its implications for primate evolution

Early Miocene fossils from Rusinga Island, Kenya, provide some of the best evidence for catarrhine evolution and diversification, and, together with more than eighty-five other mammalian species, form an important comparative reference for understanding faunal succession in East Africa. While there is consensus over the stratigraphic position of most of Rusinga's volcaniclastic deposits, the lacustrine Kulu Formation has been placed in various parts of the geological sequence by different researchers. To resolve this discrepancy, we conducted detailed geological analyses which indicate that the Kulu Formation was formed in the Early Miocene during a period of volcanic inactivity and subsidence following the early, mainly explosive hyper-alkaline phase of the Kisingiri complex and prior to the final eruptions of nephelinitic lavas. The underlying Hiwegi and older formations were locally deformed and deeply eroded before sedimentation began in the Kulu basin, so that the Kulu sediments may be significantly younger than the 17.8 Ma Hiwegi Formation and not much older than the overlying Kiangata Agglomerata-Lunene Lava series, loosely dated to ca. 15 Ma. The overall similarities between Kulu and Hiwegi faunas imply long-term ecological stability in this region. Our stratigraphic interpretation suggests that the Kulu fauna is contemporaneous with faunas from West Turkana, implying that differences between these assemblages—particularly in the primate communities—reflect paleobiogeographic and/or paleocological differences. Finally, the position of the Kulu Formation restricts the time frame during which the substantial faunal turnover seen in the differences between the primate and mammalian communities of Rusinga and Maboko Islands could have occurred.     

Callistoe vincei, a new Proborhyaenidae (Borhyaenoidea, Metatheria, Mammalia) from the Early Eocene of Argentina

Callistoe vincei nov. gen., nov. sp. is a new South American carnivorous marsupial (Proborhyaenidae, Borhyaenoidea) from Salta Province (Argentina). It is preliminarily described and its phylogenetic relationships with other borhyaenoids are analyzed. The holotype is a complete skull with almost complete postcranial skeleton (missing the pelvis and the tail). It is from the Lumbrera Formation (Early Eocene of northwestern Argentina). It represents the most complete proborhyaenid specimen ever discovered and one of the best-preserved borhyaenoid. In the present paper we analyze the major cranial and dental features, the essential elements to compare C. vincei to Arminiheringia auceta, a Casamayoran proborhyaenid of Patagonia. C. vincei is smaller, much more gracile; its skull is narrower; its lower canines are not procumbent; the metacrista of M3 is U-shaped; the postmetacrista of M4 is present and the mandibular symphysis is shorter. This new material allows reconsideration of some dental traits proposed to diagnose the Proborhyaenidae such as the number of incisors and the open-rooted canines.     

Revision of the scorpionfly family Holcorpidae (Mecoptera), with description of a new species from Early Eocene McAbee,British Columbia,Canada

The scorpionfly family Holcorpidae (Mecoptera) has been informally discussed since the early 1960’s, but a detailed treatment in accordance with the provisions of the International Code of Zoological Nomenclature for naming families was not provided until Willmann did so in 1989; he is recognized as author of the family. The Holcorpidae concept is revised here based on examination of its two specimens of Holcorpa maculosa from the Late Eocene of Florissant, Colorado, and a third, new specimen from the Early Eocene Okanagan Highlands locality at McAbee, British Columbia, Canada. This new specimen belongs to a second, new species, which is described here, Holcorpa dillhoffi n. sp.     

Echinoderm faunas from the Lower Cretaceous (Aptian–Albian) of Alexander Island,Antarctica

Abstract: Strata assigned to the Fossil Bluff Group on Alexander Island, Antarctica, contain Aptian to Albian high‐latitude echinoderm faunas that lived at palaeolatitudes greater than 60 degrees south. The Pluto Glacier Formation, of essentially Aptian age, yields a deep‐water assemblage that includes two ophiuroids, an ophiacanthid and a representative of the ophiolepidid genus Mesophiomusium, both represented by partially articulated specimens. The echinoid fauna includes a new genus of diadematoid, Australidiadema, and a new genus of disasteroid, Notidisaster, which extend the record of both groups into the southern hemisphere. The overlying Neptune Glacier Formation, of late Albian age, yields only spatangoids which are common but rarely well enough preserved to be identified even to genus level, although at least some belong to the genus Hemiaster.