Anatomy of the Nasal and Auditory Regions of the Fossil Lagomorph Palaeolagus haydeni: Systematic and Evolutionary Implications

Palaeolagus, a late Eocene to early Miocene North American lagomorph genus, represented by numerous and well-preserved specimens, has been long considered a basal leporid, although it is currently understood as a stem lagomorph. Based on micro-computed tomography (μCT) data and 3D reconstructions, here we present the first description of intracranial structures of the nasal and auditory regions of a complete skull of Palaeolagus haydeni from the early Oligocene of Nebraska. Although Palaeolagus haydeni shows a puzzling mixture of extant leporid and ochotonid characters, it helps to polarize and re-evaluate already known lagomorph intracranial characters based on outgroup comparison with Rodentia and Scandentia. Common derived features of Palaeolagus haydeni and extant Lagomorpha are the dendritic maxilloturbinal and the excavated nasoturbinal that contacts the lamina semicircularis. Generally, Palaeolagus haydeni and Leporidae have several characters in common, some of which are certainly plesiomorphic (e.g., thin wall of bulla tympani and flat conic cochlea). Palaeolagus haydeni resembles Leporidae in having an interturbinal between the two frontoturbinals, and three ethmoturbinals plus one interturbinal between ethmoturbinal I and II. Now, this should also be regarded as a plesiomorphic grundplan pattern for Leporidae whereas ochotonids are derived from the lagomorph grundplan as concerns the number of frontoturbinals. Concerning the middle ear, Palaeolagus haydeni significantly contributes to the polarization of the anterior anchoring of the malleus in extant lagomorphs. Palaeolagus haydeni resembles the pattern observed in early ontogenetic stages of Ochotonidae, i.e., the attachment of the malleus to the ectotympanic via a short processus anterior. The patterns in adult ochotonids and leporids now can be regarded as two different and apomorphic character states. Autapomorphic characters of Palaeolagus haydeni are the reduced frontoturbinal 2 and the additional anterolaterally oriented process of the lamina semicircularis. Interestingly, among the investigated intracranial structures the loss of the secondary crus commune is the only apomorphic grundplan character of crown Lagomorpha.

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Late Eocene – Early Miocene facies and stratigraphic development, Taranaki Basin, New Zealand: the transition to plate boundary tectonics during regional transgression

Geological Magazine ◽

10.1017/s0016756818000997 ◽

2019 ◽

Vol 156 (10) ◽

pp. 1751-1770 ◽

Cited By ~ 3

Author(s):

Dominic P. Strogen ◽

Karen E. Higgs ◽

Angela G. Griffin ◽

Hugh E. G. Morgans

Keyword(s):

New Zealand ◽

Tectonic Setting ◽

Plate Boundary ◽

Late Eocene ◽

Early Miocene ◽

Fault System ◽

Initial Development ◽

Early Oligocene ◽

Well Data ◽

Latest Eocene

AbstractEight latest Eocene to earliest Miocene stratigraphic surfaces have been identified in petroleum well data from the Taranaki Basin, New Zealand. These surfaces define seven regional sedimentary packages, of variable thickness and lithofacies, forming a mixed siliciclastic–carbonate system. The evolving tectonic setting, particularly the initial development of the Australian–Pacific convergent margin, controlled geographic, stratigraphic and facies variability. This tectonic signal overprinted a regional transgressive trend that culminated in latest Oligocene times. The earliest influence of active compressional tectonics is reflected in the preservation of latest Eocene – Early Oligocene deepwater sediments in the northern Taranaki Basin. Thickness patterns for all mid Oligocene units onwards show a shift in sedimentation to the eastern Taranaki Basin, controlled by reverse movement on the Taranaki Fault System. This resulted in the deposition of a thick sedimentary wedge, initially of coarse clastic sediments, later carbonate dominated, in the foredeep close to the fault. In contrast, Oligocene active normal faulting in a small sub-basin in the south may represent the most northerly evidence for rifting in southern Zealandia, related to Emerald Basin formation. The Early Miocene period saw a return to clastic-dominated deposition, the onset of regional regression and the southward propagation of compressional tectonics.

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DEVELOPMENT OF THE TERTIARY OFFSHORE PAPUAN BASIN

The APPEA Journal ◽

10.1071/aj74006 ◽

1975 ◽

Vol 15 (1) ◽

pp. 55 ◽

Cited By ~ 2

Author(s):

N. C. Tallis

Keyword(s):

Late Eocene ◽

Early Miocene ◽

Second Phase ◽

The West ◽

Fine Grained ◽

Early Oligocene ◽

Coral Sea ◽

Clastic Sediments ◽

Marine Seismic ◽

Rigid Segment

Marine seismic studies combined with wildcat drilling in the Gulf of Papua have provided a comprehensive insight into the geology of the offshore Papuan Basin. The Basin adjoins a downwarped but structurally rigid segment of the Australian continental shield in the west, and the Coral Sea Basin in the southeast. It incorporates arcuate geosynclinal development eastward and northward beyond the continental margin. The pre-Tertiary history is relatively obscure. Jurassic-Lower Cretaceous clastic sediments overlie granites and volcanics of the continental shield in the west. Eastward, the record is masked by great thicknesses of Tertiary strata, and the pre-Tertiary may be represented in outcrop by a metamorphic series of indeterminate age.The Tertiary offshore basin developed in three distinct phases, commencing in Late Cretaceous/Early Eocene time, when seas transgressed from east to west across a peneplaned surface. An eastward-thickening wedge of argillaceous limestones and cherts was deposited. Regression and erosion occurred in Late Eocene/Early Oligocene time, possibly in association with upwarp of the oceanic crust, which created an eastern volcanic borderland. Typical orthogeosynclinal sedimentation followed in Early Miocene time, with reef, shoal and pelagic limestones deposited marginal to the stable western (continental) shelf, and with prolific volcanism associated with the eastern (oceanic) flank. This volcanism was the source for a thick pile of mudstone-greywacke sediments which was deposited in an intermediate eugeosyncline.This second phase was modified in Late Miocene time by regional uplift, and by development of the Central Mountain geanticlinal belt. This created an immense southeasterly pro-grading system which rapidly buried the Early Miocene profile. These fine grained clastic Plio-Pleistocene sediments have been highly deformed by gravitational and diapiric influences in the east-central portion of the basin. Huge volumes of sediment are still being transported southeastward into the Coral Sea Basin.

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Tertiary extension and tilting in the Queen Charlotte Islands, evidence from dyke swarms and their paleomagnetism

Canadian Journal of Earth Sciences ◽

10.1139/e92-147 ◽

1992 ◽

Vol 29 (9) ◽

pp. 1878-1898 ◽

Cited By ~ 12

Author(s):

E. Irving ◽

J. G. Souther ◽

J. Baker

Keyword(s):

North American ◽

Late Eocene ◽

North American Plate ◽

Western Margin ◽

Queen Charlotte Islands ◽

The North ◽

Early Oligocene ◽

Magnetic Stability ◽

Transform Margin ◽

Dyke Swarms

The Queen Charlotte Islands form the western margin of the Tertiary Queen Charlotte Basin, which is situated on the western margin of the North American Plate. They contain seven major dyke swarms of Late Eocene to Miocene age, a period when the relative motions of the Pacific and the North American plates in this region were dominantly dextral strike slip (transform margin), with intervals of highly oblique divergence and convergence. Within each swarm, dykes have a systematic trend. However, trends vary from swarm to swarm, indicating that the stress field varied. A total of 678 cores (1352 specimens) were collected from 129 dykes in six swarms over a distance of about 200 km. Magnetic stability is variable. One hundred and one dykes yielded records of the paleofield. Data are also reported from an Oligocene pluton (5 sites, 27 cores, 52 specimens) and Miocene lavas (8 sites, 52 cores, 101 specimens). Both normal and reversed magnetizations occur, but irrespective of sign, the mean directions of remanent magnetization of each swarm and of the pluton and the lavas have systematically steeper inclinations than the value calculated from coeval rocks in North America. To explain this it is proposed that, after dyke emplacement, the sampling areas were tilted to the north or northwest by amounts that vary between 9 and 16°. Apparently, crustal tilting, similar in magnitude and direction, extended over distances of approximately 200 km. This cannot reflect tilting of a single block. Instead, it is argued that at least the southern Queen Charlotte Islands underwent considerable northerly or north-northwesterly directed extension and normal block faulting, which followed and in part was concurrent with the formation of widespread mid-Tertiary dyke swarms, plutons and lava flows. Making use of the fact that dykes propagate perpendicular to the direction of extension, and combining previously measured dyke orientations with paleomagnetic data, three stages of extension are proposed: east–west extension sometime during the Late Eocene to Early Oligocene; north–south extension sometime in the interval Late Oligocene to Early Miocene; and northwest–southeast extension sometime during Late Miocene or later time.

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A comparative description of the mesosomal musculature in Sphecidae and Ampulicidae (Hymenoptera, Apoidea) using 3D techniques

Deutsche Entomologische Zeitschrift ◽

10.3897/dez.67.49493 ◽

2020 ◽

Vol 67 (1) ◽

pp. 51-67

Author(s):

Maraike Willsch ◽

Frank Friedrich ◽

Daniel Baum ◽

Ivo Jurisch ◽

Michael Ohl

Keyword(s):

Computed Tomography ◽

Abdominal Segment ◽

Micro Computed Tomography ◽

3D Reconstructions ◽

Anatomy Ontology ◽

Morphological Studies ◽

Skeletal Musculature ◽

Ampulex Compressa ◽

Comparative Description ◽

Structural Aspects

Conflicting hypotheses about the relationships among the major lineages of aculeate Hymenoptera clearly show the necessity of detailed comparative morphological studies. Using micro-computed tomography and 3D reconstructions, the skeletal musculature of the meso- and metathorax and the first and second abdominal segment in Apoidea are described. Females of Sceliphron destillatorium, Sphex (Fernaldina) lucae (both Sphecidae), and Ampulex compressa (Ampulicidae) were examined. The morphological terminology provided by the Hymenoptera Anatomy Ontology is used. Up to 42 muscles were found. The three species differ in certain numerical and structural aspects. Ampulicidae differs significantly from Sphecidae in the metathorax and the anterior abdomen. The metapleural apodeme and paracoxal ridge are weakly developed in Ampulicidae, which affect some muscular structures. Furthermore, the muscles that insert on the coxae and trochanters are broader and longer in Ampulicidae. A conspicuous characteristic of Sphecidae is the absence of the metaphragma. Overall, we identified four hitherto unrecognized muscles. Our work suggests additional investigations on structures discussed in this paper.

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CT-Informed Skull Osteology of Palaeolagus haydeni (Mammalia: Lagomorpha) and Its Bearing on the Reconstruction of the Early Lagomorph Body Plan

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.634757 ◽

2021 ◽

Vol 9 ◽

Author(s):

Andrzej S. Wolniewicz ◽

Łucja Fostowicz-Frelik

Keyword(s):

Common Ancestor ◽

Late Eocene ◽

Last Common Ancestor ◽

Western North America ◽

Micro Computed Tomography ◽

Early Oligocene ◽

Phylogenetic Status ◽

Herbivorous Mammals ◽

Latest Eocene ◽

First Time

Lagomorpha is a clade of herbivorous mammals nested within Euarchontoglires, one of the major placental groups represented today. It comprises two extant families with markedly different body plans: the long-eared and long-limbed Leporidae (hares and rabbits) and the short-eared and short-limbed Ochotonidae (pikas). These two lagomorph lineages diverged probably during the latest Eocene/early Oligocene, but it is unclear whether the last common ancestor of crown lagomorphs was more leporid- or more ochotonid-like in morphology. Palaeolagus, an early lagomorph dominant in western North America from the late Eocene to Oligocene is of particular importance for addressing this controversy. Here, we present new and comprehensive data on the cranial anatomy of Palaeolagus haydeni, the type species for the genus, based on micro-computed tomography (μCT). Our μCT data allow us to confirm, revise and score for the very first time the states of several leporid-like and ochotonid-like characters in the skull of Palaeolagus. This mixed cranial architecture differentiates Palaeolagus from the crown groups of Lagomorpha and supports its phylogenetic status as a stem taxon.

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Late Eocene–early Miocene evolution of the southern Australian subtropical front: a marine palynological approach

Journal of Micropalaeontology ◽

10.5194/jm-40-175-2021 ◽

2021 ◽

Vol 40 (2) ◽

pp. 175-193

Author(s):

Frida S. Hoem ◽

Isabel Sauermilch ◽

Suning Hou ◽

Henk Brinkhuis ◽

Francesca Sangiorgi ◽

...

Keyword(s):

Southern Ocean ◽

Late Eocene ◽

Early Miocene ◽

Ocean Drilling Program ◽

Subtropical Front ◽

Leeuwin Current ◽

Ocean Drilling ◽

Early Oligocene ◽

Integrated Ocean Drilling Program ◽

Oceanographic Conditions

Abstract. Improvements in our capability to reconstruct ancient surface-ocean conditions based on organic-walled dinoflagellate cyst (dinocyst) assemblages from the Southern Ocean provide an opportunity to better establish past position, strength and oceanography of the subtropical front (STF). Here, we aim to reconstruct the late Eocene to early Miocene (37–20 Ma) depositional and palaeoceanographic history of the STF in the context of the evolving Tasmanian Gateway as well as the potential influence of Antarctic circumpolar flow and intense waxing and waning of ice. We approach this by combining information from seismic lines (revisiting existing data and generating new marine palynological data from Ocean Drilling Program (ODP) Hole 1168A) in the western Tasmanian continental slope. We apply improved taxonomic insights and palaeoecological models to reconstruct the sea surface palaeoenvironmental evolution. Late Eocene–early Oligocene (37–30.5 Ma) assemblages show a progressive transition from dominant terrestrial palynomorphs and inner-neritic dinocyst taxa as well as cysts produced by heterotrophic dinoflagellates to predominantly outer-neritic/oceanic autotrophic taxa. This transition reflects the progressive deepening of the western Tasmanian continental margin, an interpretation supported by our new seismic investigations. The dominance of autotrophic species like Spiniferites spp. and Operculodinium spp. reflects relatively oligotrophic conditions, like those of regions north of the modern-day STF. The increased abundance in the earliest Miocene of Nematosphaeropsis labyrinthus, typical for modern subantarctic zone (frontal) conditions, indicates a cooling and/or closer proximity of the STF to the site . The absence of major shifts in dinocyst assemblages contrasts with other records in the region and suggests that small changes in surface oceanographic conditions occurred during the Oligocene. Despite the relatively southerly (63–55∘ S) location of Site 1168, the rather stable oceanographic conditions reflect the continued influence of the proto-Leeuwin Current along the southern Australian coast as Australia continued to drift northward. The relatively “warm” dinocyst assemblages at ODP Site 1168, compared with the cold assemblages at Antarctic Integrated Ocean Drilling Program (IODP) Site U1356, testify to the establishment of a pronounced latitudinal temperature gradient in the Oligocene Southern Ocean.

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New turtles (Chelonia) from the late Eocene through late Miocene of the Panama Canal Basin

Journal of Paleontology ◽

10.1666/11-106.1 ◽

2012 ◽

Vol 86 (3) ◽

pp. 539-557 ◽

Cited By ~ 26

Author(s):

Edwin Cadena ◽

Jason R. Bourque ◽

Aldo F. Rincon ◽

Jonathan I. Bloch ◽

Carlos A. Jaramillo ◽

...

Keyword(s):

Late Miocene ◽

Late Eocene ◽

Panama Canal ◽

Early Miocene ◽

South American ◽

Early Oligocene ◽

Isthmus Of Panama ◽

Early Arrival ◽

The Tropics ◽

First Contact

Four distinct fossil turtle assemblages (Chelonia) are recognized from the Panama Canal Basin. The oldest, from the late Eocene–early Oligocene Gatuncillo Formation, is dominated by podocnemidid pleurodires. The early Miocene Culebra Formation includes both podocnemidids and trionychids. The early to middle Miocene Cucaracha Formation includes taxa classified in Geoemydidae (including Rhinoclemmys panamaensis n. sp.), Kinosternidae (represented by Staurotypus moschus n. sp.), large testudinids, trionychids, and podocnemidids, and finally, the late Miocene Gatun Formation records cheloniid sea turtles. These fossils include the oldest known representatives of Rhinoclemmys, the oldest record of kinosternids in Central America with a more extensive southern paleodistribution for Staurotypus and staurotypines in general, early occurrences of giant tortoises in the Neotropics, the oldest occurrence of soft-shell turtles in the tropics, the oldest late Eocene–early Oligocene Neotropical occurrences of podocnemidids. The Panamanian fossil turtles represent clades that are primarily endemic to North America, showing their very early arrival into the Neotropics prior to the complete emergence of the Isthmus of Panama, as well as their first contact with Caribbean-South American pleurodires by the early Miocene.

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Kinematic analysis and tertiary evolution of the Lesvos ophiolites and metamorphic sole (Aegean sea, Greece)

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17022 ◽

2001 ◽

Vol 34 (1) ◽

pp. 267 ◽

Cited By ~ 3

Author(s):

D. MOUNTRAKIS ◽

E. THOMAIDOU ◽

N. ZOUROS ◽

A. KILIAS

Keyword(s):

Continental Margin ◽

Aegean Sea ◽

Late Eocene ◽

Early Miocene ◽

Tectonic Event ◽

Detachment Faults ◽

Early Oligocene ◽

Tectonic Events ◽

Extensional Tectonic ◽

Thrust Sheets

In Lesvos Island, the ophiolites and the metamorphic sole are emplaced onto the Permo-Triassic continental margin rocks. New field data on the Tertiary kinematics distinguished three successive tectonic events that affected the Lesvos ophiolites and sole. The Dl compressional event took place in Late Eocene - Early Oligocene and produced several thrust sheets and their stacking over the continental margin. The thickening of the crust after the Dl event, was followed by an important extensional tectonic event (D2) in semi-ductile conditions in Oligocene-Early Miocene times, which produced the uplift process of the orogen and the lateral rejection of the tectonic nappes through large extensional semi-ductile faults of low angle (detachment faults) and caused the exhumation of the underlying continental margin rocks in the form of a tectonic window. This extensional tectonic event led to the thinning of the crust in the wider area of Lesvos and probably caused the Early Miocene volcanic activity. The last D3 extensional tectonic event, took place in brittle conditions and represents the neotectonic regime in Late Miocene-Recent times.

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Middle Eocene through Early Miocene North American Vegetational History: 50-16.3 Ma

Late Cretaceous and Cenozoic History of North American Vegetation (North of Mexico) ◽

10.1093/oso/9780195113426.003.0009 ◽

1999 ◽

Author(s):

Alan Graham

Keyword(s):

Sierra Nevada ◽

Rocky Mountains ◽

Middle Eocene ◽

Co2 Concentration ◽

Late Eocene ◽

Early Miocene ◽

Northern Rocky Mountains ◽

Atmospheric Circulation Patterns ◽

Early Oligocene ◽

Latest Eocene

During the Middle Eocene through the Early Miocene, erosion of the Appalachian Mountains exceeded uplift and there was a net reduction in elevation. In the Rocky Mountains uplift continued through the Middle Eocene (end of the Laramide orogeny), waned in the Middle Tertiary, and then increased beginning at about 10 Ma. Earlier reconstructions placed paleoelevations in the Rocky Mountains during the Middle Eocene through the Early Miocene at approximately half the present relief. The maximum elevation in the Front Ranges during the latest Eocene was estimated at ~2500 m (~8000 ft; MacGinitie, 1953). Recent approximations are for nearly modern elevations in several areas by the Eocene-Oligocene. Extensive Eocene volcanism deposited ash and blocked drainage systems, augmenting uplift and facilitating the preservation of extensive fossil floras and faunas. In the far west the beginning of Tertiary volcanism in the Sierra Nevada is dated at ~ 33 Ma near the Eocene-Oligocene boundary. A drying trend becomes evident in the Middle Eocene and reduced moisture, along with the waning of volcanic activity in the Oligocene, restricted conditions favorable to fossilization. The number of Oligocene floras in the northern Rocky Mountains is considerably fewer than in younger deposits to the west. In the absence of extensive plate reorganization and orogeny, CO2 concentration decreased, which contributed to a temperature decline that continued through the Cenozoic and intensified in the Late Tertiary. Recall from Chapter 2 (sections on orogeny and volcanism) that uplift plays a role in determining long-term climate by creating rainshadows, altering atmospheric circulation patterns, and increasing the erosion of silicate rocks that causes a drawdown of CO2. This allows heat to escape from the troposphere and results in lower temperatures. Marine benthic temperatures were ~10°C in the early Late Eocene and ~2°C near the Eocene-Oligocene boundary, assuming an essentially ice-free Earth during that time, and increased to ~5-6°Cnear the end of the Early Miocene. Temperatures over land in the midnorthern latitudes are estimated to have dropped by ~12°C between the Late Eocene and Early Oligocene (Wolfe, 1992a).

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