The Evolutionary History and Diversity of Australian Mammals

1999 ◽  
Vol 21 (1) ◽  
pp. 1
Author(s):  
M. Archer ◽  
R. Arena ◽  
M. Bassarova ◽  
K. Black ◽  
J. Brammall ◽  
...  
Keyword(s):  
Evolutionary History ◽  
Middle Miocene ◽  
Middle Eocene ◽  
Late Triassic ◽  
Early Eocene ◽  
Late Oligocene ◽  
Mammal Evolution ◽  
Initial Description ◽  
Fossil Records ◽  
First Time

Palaeodiversity and relationships of all groups of Australian mammals are reviewed. The fossil record spanning this time is of variable quality. 'Dark Ages' about which nothing is known in terms of Australian mammal evolution include the late Triassic to late Jurassic, late Cretaceous to late Paleocene and middle Eocene to middle Oligocene. Very little is known about the early Cretaceous and late Miocene. The late Oligocene to middle Miocene record documents the highest levels of biodiversity known for the continent, comparable to that which characterises the lowland rainforests of Borneo and Brazil. Order Monotremata spans at least the last 110 million years and includes four families. The enigmatic Ausktribosphenos from 115 million-year-old sediments in Victoria may represent an archaic monotreme, specialised peramurid or previously undocumented order of mammals but is unlikely to represent a placental as suggested in the initial description. Order Microbiotheria is represented in the early Eocene (~55 mya) by two genera similar in morphology to early Eocene taxa from Argentina. Order Peramelemorphia spans the early Eocene to Holocene and includes at least five families. Order Dasyuromorphia spans at least the late Oligocene to Holocene and includes at least three families. Other dasyuromorphian-like marsupials are indeterminate in terms of family-level affinities. Order Notoryctemorphia spans the early Miocene to Holocene with one family. Order Yalkaparidontia spans the late Oligocene to middle Miocene with one genus. Order Diprotodontia spans the late Oligocene to Holocene, represented throughout by three major groups: Phalangerida (eight families), Vombatomorphia (seven families) and Macropodoidea (at least three families). A possible placental condylarth (Tingamarra) has been recorded from the early Eocene. An archaeonycteridid bat (Australonycteris) is known from the early Eocene. Among bats, the late Oligocene to middle Miocene is dominated by rhinolophoids, many of which have European, Asian and African affinities. Mystacinids, megadermatids, hipposiderids and molossids are well-represented in the Oligocene to Miocene deposits. Vespertilionids are uncommon in the Oligocene to Miocene but become more diverse in the Pliocene to Holocene. Emballonurids and rhinolophids appear for the first time in the Plio-Pleistocene. Pteropodids are unknown prior to the Holocene. Murids span the early Pliocene to Holocene. In the oldest assemblage at Riversleigh, one undescribed lineage resembles archaic forms otherwise only known from the fossil records of Africa and Eurasia.

scholarly journals Re-study of some dinoflagellate cysts from the Oligocene and Miocene of Germany

1984 ◽  
Vol 3 (2) ◽  
pp. 73-94 ◽  
Author(s):  
William A. S. Sarjeant
Keyword(s):  
Middle Miocene ◽  
Type Material ◽  
New Combination ◽  
Late Oligocene ◽  
Dinoflagellate Cysts ◽  
Dinoflagellate Cyst ◽  
Northwest Germany ◽  
Senior Synonym ◽  
First Time

Abstract. The type material of six dinoflagellate cyst species from the Late Oligocene to Middle Miocene of northwest Germany, described originally by Gerlach (1961), is reillustrated and redescribed. It is shown to include representatives of nine species. Areosphaeridium (ex: Baltisphaeridium) pectiniforme is found to be a senior synonym of Areosphaeridium multicornutum Eaton. Systematophora placacantha is considered to be a senior synonym of Cleistosphaeridium (ex: Baltisphaeridium) panniforme (Gerlach). The new combination Rhynchodiniopsis tenuitabulata (Gerlarch) is proposed. Revised diagnoses for these three species and for Leptodinium membranigerum (Gerlach), Achomosphaera triangulata (Gerlach) and Lejeunecysta hyalina (Gerlach) are proposed. The morphology of a form described here for the first time, and tentatively attributed to Phthanoperidinium, is considered perhaps to imply a separate origin for the Phthanoperidiniaceae: for that reason familial, rather than tribal, rank is preferred for that group. The stratigraphical ranges of the nine species here recognised and of two others of Gerlach’s species redescribed in earlier papers are detailed; elimination of misattributed forms means that these ranges are shorter than the published literature suggests.

Detrital zircon provenance of the Indus Group, Ladakh, NW India: Implications for the timing of the India-Asia collision and other syn-orogenic processes

2020 ◽  
Author(s):  
Gourab Bhattacharya ◽  
Delores M. Robinson ◽  
Matthew M. Wielicki
Keyword(s):  
Detrital Zircon ◽  
Indus Basin ◽  
Indian Plate ◽  
Early Eocene ◽  
Late Oligocene ◽  
Data Set ◽  
Ca 50 ◽  
First Arrival ◽  
Uplift And Erosion ◽  
First Time

The timing of the India-Asia collision is greatly debated and is critical for elucidating early orogenic processes. This study documents, for the first time, evidence of India-Asia detrital mixing in the continental sedimentary rocks of the India-Asia collision zone of NW India at ca. 50 Ma and presents the largest detrital zircon (DZ) U-Pb age data set (n = 1225) from the region. Our DZ U-Pb age spectra from the early Eocene−late Oligocene continental Indus Group reveal a hybrid India-Asia provenance. The dominant Mesozoic−Cenozoic DZ peaks are ca. 107 Ma, 100−80 Ma, 60−50 Ma, 40 Ma, and 26 Ma, and they are mostly derived from Asia. The primary Precambrian DZ peaks are ca. 2.5 Ga, 1.2−0.95 Ga, 0.78−0.63 Ga, and 0.55 Ga and are representative of Tethyan Himalayan rocks on Greater India. Maximum depositional ages (MDAs) for four key Indus Group units, the Nurla, Hemis, Basgo, and Temesgam Formations, support syn-orogenic deposition in the Indus Basin from early Eocene to at least late Oligocene time. The Nurla Formation, with an MDA of ca. 50 Ma, records the first arrival of Greater Indian zircons on the Asian plate, thereby indicating uplift and erosion along the subducting Indian plate and collision of India with Asia by ca. 50 Ma. The ca. 27−26 Ma zircons in the younger late Oligocene Basgo and Temesgam Formations were contributed by the Lhasa terrane in south Tibet, which implies that the Indus River flowed from east to west across NW India at least by ca. 27 Ma.

scholarly journals The oldest known fur seal

2015 ◽  
Vol 11 (2) ◽  
pp. 20140835 ◽  
Author(s):  
Robert W. Boessenecker ◽  
Morgan Churchill
Keyword(s):  
Fossil Record ◽  
Evolutionary History ◽  
Southern California ◽  
Middle Miocene ◽  
Sea Lions ◽  
Fur Seals ◽  
Fur Seal ◽  
Fossil Records ◽  
Phylogenetic Affinities

The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect their current diversity and widespread abundance. This limited fossil record contrasts with the more complete fossil records of other pinnipeds such as walruses (Odobenidae). The oldest known otariids appear 5–6 Ma after the earliest odobenids, and the remarkably derived craniodental morphology of otariids offers few clues to their early evolutionary history and phylogenetic affinities among pinnipeds. We report a new otariid, Eotaria crypta , from the lower middle Miocene ‘Topanga’ Formation (15–17.1 Ma) of southern California, represented by a partial mandible with well-preserved dentition. Eotaria crypta is geochronologically intermediate between ‘enaliarctine’ stem pinnipedimorphs (16.6–27 Ma) and previously described otariid fossils (7.3–12.5 Ma), as well as morphologically intermediate by retaining an M 2 and a reduced M 1 metaconid cusp and lacking P 2–4 metaconid cusps. Eotaria crypta eliminates the otariid ghost lineage and confirms that otariids evolved from an ‘enaliarctine’-like ancestor.

scholarly journals New wombats from Riversleigh, northwestern Queensland, include pouch young

2018 ◽  
Author(s):  
Philippa Brewer
Keyword(s):  
Middle Miocene ◽  
Middle Eocene ◽  
Large Degree ◽  
Species Level ◽  
Late Oligocene ◽  
Additional Species ◽  
Variable Species ◽  
Degree Of Confidence ◽  
Qualitative Characters ◽  
Insight Into

Despite an estimated molecular divergence date of 40 million years (middle Eocene) between wombats and their closest living relative, the koala, the fossil record of wombats is poor. The two oldest described wombats, Nimbavombatus boodjamullensis and Rhizophascolonus crowcrofti, are both early Miocene in age. The former is known from maxillae, upper cheek teeth and isolated lower molars from Riversleigh in northwestern Queensland. The latter is known only from the isolated teeth from central Australia. Here we describe additional specimens of Rhizophascolonus from Riversleigh that are late Oligocene to middle Miocene in age as well as at least one additional species. Excitingly, the new specimens show an ontogenetic range from pouch young with occlusal cusp details intact to fully adult specimens with heavily worn teeth. The unworn teeth from Riversleigh are compared with those pouch young from two extant wombat taxa and the extant koala. In addition, comparisons of quantitative and qualitative characters of all known Rhizophascolonus specimens with other koala and wombat taxa reveal a large degree of variation in the sample of Rhizophascolonus teeth from Riversleigh. However, the number of species of Rhizophascolonus present is difficult to ascertain and it is not inconceivable that there is only one or two highly variable species present. Despite uncertainty at the species level, these new specimens provide an unprecedented insight into this enigmatic group, and we can now start to reconstruct intrafamilial relationships with a greater degree of confidence. Furthermore, occlusal morphology can now be used to help clarify interfamilial relationships in the suborder Vombatiformes, which in addition to wombats and koalas, includes five additional extinct families.

scholarly journals New wombats from Riversleigh, northwestern Queensland, include pouch young

2018 ◽  
Author(s):  
Philippa Brewer
Keyword(s):  
Middle Miocene ◽  
Middle Eocene ◽  
Large Degree ◽  
Species Level ◽  
Late Oligocene ◽  
Additional Species ◽  
Variable Species ◽  
Degree Of Confidence ◽  
Qualitative Characters ◽  
Insight Into

Despite an estimated molecular divergence date of 40 million years (middle Eocene) between wombats and their closest living relative, the koala, the fossil record of wombats is poor. The two oldest described wombats, Nimbavombatus boodjamullensis and Rhizophascolonus crowcrofti, are both early Miocene in age. The former is known from maxillae, upper cheek teeth and isolated lower molars from Riversleigh in northwestern Queensland. The latter is known only from the isolated teeth from central Australia. Here we describe additional specimens of Rhizophascolonus from Riversleigh that are late Oligocene to middle Miocene in age as well as at least one additional species. Excitingly, the new specimens show an ontogenetic range from pouch young with occlusal cusp details intact to fully adult specimens with heavily worn teeth. The unworn teeth from Riversleigh are compared with those pouch young from two extant wombat taxa and the extant koala. In addition, comparisons of quantitative and qualitative characters of all known Rhizophascolonus specimens with other koala and wombat taxa reveal a large degree of variation in the sample of Rhizophascolonus teeth from Riversleigh. However, the number of species of Rhizophascolonus present is difficult to ascertain and it is not inconceivable that there is only one or two highly variable species present. Despite uncertainty at the species level, these new specimens provide an unprecedented insight into this enigmatic group, and we can now start to reconstruct intrafamilial relationships with a greater degree of confidence. Furthermore, occlusal morphology can now be used to help clarify interfamilial relationships in the suborder Vombatiformes, which in addition to wombats and koalas, includes five additional extinct families.

scholarly journals The oldest known fur seal

2017 ◽  
Author(s):  
Robert Boessenecker ◽  
Morgan Churchill
Keyword(s):  
Fossil Record ◽  
Evolutionary History ◽  
Southern California ◽  
Middle Miocene ◽  
Sea Lions ◽  
Fur Seals ◽  
Fur Seal ◽  
Fossil Records ◽  
Phylogenetic Affinities

The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect their current diversity and widespread abundance. This limited fossil record contrasts with the more complete fossil records of other pinnipeds such as walruses (Odobenidae). The oldest known otariids appear 5-6 Ma after the earliest odobenids, and the remarkably derived craniodental morphology of otariids offers few clues to their early evolutionary history and phylogenetic affinities among pinnipeds. We report a new otariid, Eotaria crypta, from the early middle Miocene “Topanga” Formation (15-17.5 Ma) of southern California, represented by a partial mandible with well-preserved dentition. Eotaria crypta is geochronologically intermediate between “enaliarctine” stem pinnipedimorphs (16.6-27 Ma) and previously described otariid fossils (7.3-12.5 Ma), as well as morphologically intermediate by retaining an M2 and a reduced M1 metaconid cusp and lacking P2-4 metaconid cusps. Eotaria crypta eliminates the otariid ghost lineage and confirms that otariids evolved from an “enaliarctine”-like ancestor.

scholarly journals The rise to dominance of lanternfishes (Teleostei: Myctophidae) in the oceanic ecosystems: a paleontological perspective

Paleobiology ◽  
2021 ◽  
pp. 1-18
Author(s):  
Werner Schwarzhans ◽  
Giorgio Carnevale
Keyword(s):  
Ocean Circulation ◽  
Evolutionary History ◽  
Middle Miocene ◽  
Middle Eocene ◽  
Food Resource ◽  
Deep Ocean ◽  
Early Oligocene ◽  
Diatom Abundance ◽  
Deep Ocean Circulation ◽  
Upper Slope

AbstractLanternfishes currently represent one of the dominant groups of mesopelagic fishes in terms of abundance, biomass, and diversity. Their otolith record dominates pelagic sediments below 200 m in dredges, especially during the entire Neogene. Here we provide an analysis of their diversity and rise to dominance primarily based on their otolith record. The earliest unambiguous fossil myctophids are known based on otoliths from the late Paleocene and early Eocene. During their early evolutionary history, myctophids were likely not adapted to a high oceanic lifestyle but occurred over shelf and upper-slope regions, where they were locally abundant during the middle Eocene. A distinct upscaling in otolith size is observed in the early Oligocene, which also marks their earliest occurrence in bathyal sediments. We interpret this transition to be related to the change from a halothermal deep-ocean circulation to a thermohaline regime and the associated cooling of the deep ocean and rearrangement of nutrient and silica supply. The early Oligocene myctophid size acme shows a remarkable congruence with diatom abundance, the main food resource for the zooplankton and thus for myctophids and whales. The warmer late Oligocene to early middle Miocene period was characterized by an increase in disparity of myctophids but with a reduction in their otolith sizes. A second and persisting secular pulse in myctophid diversity (particularly within the genusDiaphus) and increase in size begins with the “biogenic bloom” in the late Miocene, paralleled with diatom abundance and mysticete gigantism.

scholarly journals A new Myrmecarchaea (Araneae: Archaeidae) species from Oise amber (earliest Eocene, France)

2020 ◽  
Vol 191 ◽  
pp. 24
Author(s):  
Benjamin Carbuccia ◽  
Hannah M. Wood ◽  
Christine Rollard ◽  
Andre Nel ◽  
Romain Garrouste
Keyword(s):  
Adult Male ◽  
Middle Eocene ◽  
Baltic Amber ◽  
Early Eocene ◽  
Burmese Amber ◽  
Fossil Specimen ◽  
First Occurrence ◽  
The Subject ◽  
First Time ◽  
A New Species

Extant Archaeidae, also known as pelican or assassin spiders, have an Austral distribution (South Africa, Madagascar and Australia), but were present in Eurasia during the Mesozoic and Cenozoic, as attested by fossils from Cretaceous Burmese amber (Ross A. 2019. Burmese (Myanmar) amber checklist and bibliography 2018. Palaeoentomology 2(1): 22–84) and Eocene European ambers (Wunderlich J. 2004. Fossil spiders in amber and copal: conclusions, revisions, new taxa and family diagnoses of fossil and extant taxa. Hirschberg-Leutershausen: Ed. Joerg Wunderlich, 1893 p.). They have been known to occur in Oise amber (Ypresian, early Eocene, MP7), from northern France. However, they are not abundant in Oise amber, and have been the subject of few studies until now. Here, we describe the only well-preserved, almost complete, archaeid fossil specimen. This adult male is described as Myrmecarchaea antecessor sp. nov, based on the presence of unique morphological features. The elongate petiolus and extremely long legs are characteristic of the genus Myrmecarchaea from the Middle Eocene Baltic amber. However, unique traits such as the thick, stout petiolus and the extremely elongated, posteriorly tapering cephalothorax distinguish it from the other species of Myrmecarchaea. This specimen is of high interest, as besides being a new species, it is also the first documented adult male in the genus, allowing us to observe sexual characters for the first time. Furthermore, it is the first occurrence of this genus outside Baltic amber, showing affinities between Oise and Baltic ambers, which are, otherwise, very different in their faunistic compositions, and further extends the known past range of the archaeid spiders.

Metamorphic constraints on the thermal evolution of the central Himalayan Orogen

1988 ◽  
Vol 326 (1589) ◽  
pp. 257-280 ◽  
Keyword(s):  
Middle Miocene ◽  
Thermal Evolution ◽  
Middle Eocene ◽  
Structural Evolution ◽  
Late Oligocene ◽  
Main Central Thrust ◽  
Early Stages ◽  
Early Oligocene ◽  
Mineral Assemblages ◽  
Early Late

Recent studies that integrate conventional thermobarometry of pelitic mineral assemblages with thermodynamic modeling of garnet zoning reveal complex Tertiary P -T paths for the Greater Himalayan metamorphic sequence in the central Himalaya. Viewed in light of our current understanding of the structural evolution of the Himalaya, these data provide insights into the relations between tectonic and thermal processes during orogenesis. In this paper, we present an interpretive model for tectonothermal evolution of the Greater Himalaya in the central part of the range. This model involves: (1) middle Eocene—early Oligocene burial to depths of more than 30 km during the early stages of collision between India and Asia; (2) early—late Oligocene uplift and cooling; (3) late Oligocene heating and renewed burial synchronous with the early stages of anatectic melting and leucogranite plutonism; (4) latest Oligocene-middle Miocene rapid uplift and continued leucogranite production associated with ramping on the structurally lower Main Central Thrust and tectonic denudation on structurally higher low-angle detachment systems; and (5) middle Miocene—Recent rapid cooling during the final stages of uplift to the surface.

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