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 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.

Fur Seals and Sea Lions

2013 ◽  
Author(s):  
Roger Kirkwood ◽  
Simon Goldsworthy
Keyword(s):  
Evolutionary Ecology ◽  
Conservation Status ◽  
Sea Lions ◽  
Australian Sea Lion ◽  
Fur Seals ◽  
Fur Seal ◽  
History Of ◽  
Near Shore ◽  
New Zealand Fur Seal ◽  
Near Extinction

Fur seals and sea lions are charismatic, large carnivores that engage us with both their skill and playful antics. Although all species in Australian waters were harvested to near extinction 200 years ago, fur seals are recovering and are now common in near-shore waters across southern Australia. Sea lions, however, are endangered. Their populations appear not to have recovered like fur seals and are declining at some locations. Fur seals and sea lions are important top level predators and play an important role in Australia’s temperate marine ecosystems. Key threats they currently face relate to human activities, particularly interactions with fisheries. This book outlines the comparative evolutionary ecology, biology, life-history, behaviour, conservation status, threats, history of human interactions and latest research on the three species of otariids that live in the waters of southern Australia: the Australian fur seal, New Zealand fur seal and Australian sea lion. It also includes brief descriptions of Antarctic and Subantarctic seals that occupy the Antarctic pack-ice and remote Australian territories of Macquarie Island and Heard Island.

scholarly journals Fur seals do, but sea lions don't — cross taxa insights into exhalation during ascent from dives

2021 ◽  
Vol 376 (1830) ◽  
pp. 20200219 ◽  
Author(s):  
Sascha K. Hooker ◽  
Russel D. Andrews ◽  
John P. Y. Arnould ◽  
Marthán N. Bester ◽  
Randall W. Davis ◽  
...  
Keyword(s):  
Shallow Water ◽  
Decompression Sickness ◽  
Mammal Species ◽  
Free Living ◽  
Video Cameras ◽  
Sea Lions ◽  
Fur Seals ◽  
Fur Seal ◽  
The Antarctic ◽  
Management Issues

Management of gases during diving is not well understood across marine mammal species. Prior to diving, phocid (true) seals generally exhale, a behaviour thought to assist with the prevention of decompression sickness. Otariid seals (fur seals and sea lions) have a greater reliance on their lung oxygen stores, and inhale prior to diving. One otariid, the Antarctic fur seal ( Arctocephalus gazella ), then exhales during the final 50–85% of the return to the surface, which may prevent another gas management issue: shallow-water blackout. Here, we compare data collected from animal-attached tags (video cameras, hydrophones and conductivity sensors) deployed on a suite of otariid seal species to examine the ubiquity of ascent exhalations for this group. We find evidence for ascent exhalations across four fur seal species, but that such exhalations are absent for three sea lion species. Fur seals and sea lions are no longer genetically separated into distinct subfamilies, but are morphologically distinguished by the thick underfur layer of fur seals. Together with their smaller size and energetic dives, we suggest their air-filled fur might underlie the need to perform these exhalations, although whether to reduce buoyancy and ascent speed, for the avoidance of shallow-water blackout or to prevent other cardiovascular management issues in their diving remains unclear. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

Fur seals and sea lions (family Otariidae) on the breakwaters at Adelaide

2018 ◽  
Vol 40 (2) ◽  
pp. 157
Author(s):  
Peter D. Shaughnessy ◽  
Mike Bossley ◽  
A. O. Nicholls
Keyword(s):  
Linear Model ◽  
River Estuary ◽  
Management Plan ◽  
Annual Trend ◽  
Sea Lions ◽  
Neophoca Cinerea ◽  
Fur Seals ◽  
Fur Seal ◽  
Harbor Area

Long-nosed fur seals (Arctocephalus forsteri) and Australian sea lions (Neophoca cinerea) on the breakwaters at the mouth of the Port River estuary at Adelaide’s Outer Harbor were counted from 2004 to 2015. Observed counts were modelled using a generalised linear model. Fur seal numbers have been increasing since 2011; for sea lions there was a small discernible annual trend in counts. Counts of fur seals varied seasonally; most annual maxima were in August or September with modelled peak numbers around 9–11 September. The maximum count of fur seals was 79 in September 2015. For sea lions, the model predicts annual peaks in the period 28 August to 19 September. The maximum count of sea lions was nine in September 2009. The haulout sites on the Outer Harbor breakwaters are easily accessible by boats, including pleasure craft. In particular, the seaward end of the outer breakwater is a popular spot with recreational anglers whose lines are often within a few metres of the seals. We propose that a management plan should be developed involving a study of the effect of boat approaches on seals utilising the Outer Harbor area followed by education coupled with enforcement.

Australian fur seals establish haulout sites and a breeding colony in South Australia

2010 ◽  
Vol 58 (2) ◽  
pp. 94 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Jane McKenzie ◽  
Melanie L. Lancaster ◽  
Simon D. Goldsworthy ◽  
Terry E. Dennis
Keyword(s):  
Mitochondrial Dna ◽  
New Zealand ◽  
South Australia ◽  
Breeding Colony ◽  
Mitochondrial Dna Control Region ◽  
Sea Lions ◽  
Neophoca Cinerea ◽  
Fur Seals ◽  
Fur Seal ◽  
New Zealand Fur Seal

Australian fur seals (Arctocephalus pusillus doriferus) breed on Bass Strait islands in Victoria and Tasmania. They have been recorded in South Australia (SA) for many years as non-breeding visitors and on Kangaroo Island frequently since 1988, mostly in breeding colonies of the New Zealand fur seal (A. forsteri) which is the most numerous pinniped in SA. Australian fur seals have displaced New Zealand fur seals from sections of the Cape Gantheaume colony on Kangaroo Island. North Casuarina Island produced 29 Australian fur seal pups in February 2008. Australian fur seal pups were larger than New Zealand fur seal pups in the same colony and have been identified genetically using a 263-bp fragment of the mitochondrial DNA control region. North Casuarina Island has been an important breeding colony of New Zealand fur seals, but pup numbers there decreased since 1992–93 (contrary to trends in SA for New Zealand fur seals), while numbers of Australian fur seals there have increased. This study confirms that Australian fur seals breed in SA. The two fur seal species compete for space onshore at several sites. Australian fur seals may compete for food with endangered Australian sea lions (Neophoca cinerea) because both are bottom feeders.

scholarly journals The inseparability of sampling and time and its influence on attempts to unify the molecular and fossil records

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 561-574 ◽  
Author(s):  
Melanie J. Hopkins ◽  
David W. Bapst ◽  
Carl Simpson ◽  
Rachel C. M. Warnock
Keyword(s):  
Mathematical Models ◽  
Fossil Record ◽  
Evolutionary History ◽  
Molecular Data ◽  
The Other ◽  
Deep Time ◽  
Approaches To Studying ◽  
Data Source ◽  
Fossil Records ◽  
Estimate Uncertainty

AbstractThe two major approaches to studying macroevolution in deep time are the fossil record and reconstructed relationships among extant taxa from molecular data. Results based on one approach sometimes conflict with those based on the other, with inconsistencies often attributed to inherent flaws of one (or the other) data source. Any contradiction between the molecular and fossil records represents a failure of our ability to understand the imperfections of our data, as both are limited reflections of the same evolutionary history. We therefore need to develop conceptual and mathematical models that jointly explain our observations in both records. Fortunately, the different limitations of each record provide an opportunity to test or calibrate the other, and new methodological developments leverage both records simultaneously. However, we must reckon with the distinct relationships between sampling and time in the fossil record and molecular phylogenies. These differences impact our recognition of baselines and the analytical incorporation of age estimate uncertainty.

scholarly journals Discriminating signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history

2015 ◽  
Vol 282 (1800) ◽  
pp. 20142245 ◽  
Author(s):  
Robert S. Sansom ◽  
Emma Randle ◽  
Philip C. J. Donoghue
Keyword(s):  
Fossil Record ◽  
Evolutionary History ◽  
Biological Factors ◽  
Sea Level Changes ◽  
Upper Ordovician ◽  
Recovery Potential ◽  
Random Models ◽  
Rock Record ◽  
Early Vertebrates ◽  
Fossil Records

The fossil record of early vertebrates has been influential in elucidating the evolutionary assembly of the gnathostome bodyplan. Understanding of the timing and tempo of vertebrate innovations remains, however, mired in a literal reading of the fossil record. Early jawless vertebrates (ostracoderms) exhibit restriction to shallow-water environments. The distribution of their stratigraphic occurrences therefore reflects not only flux in diversity, but also secular variation in facies representation of the rock record. Using stratigraphic, phylogenetic and palaeoenvironmental data, we assessed the veracity of the fossil records of the jawless relatives of jawed vertebrates (Osteostraci, Galeaspida, Thelodonti, Heterostraci). Non-random models of fossil recovery potential using Palaeozoic sea-level changes were used to calculate confidence intervals of clade origins. These intervals extend the timescale for possible origins into the Upper Ordovician; these estimates ameliorate the long ghost lineages inferred for Osteostraci, Galeaspida and Heterostraci, given their known stratigraphic occurrences and stem–gnathostome phylogeny. Diversity changes through the Silurian and Devonian were found to lie within the expected limits predicted from estimates of fossil record quality indicating that it is geological, rather than biological factors, that are responsible for shifts in diversity. Environmental restriction also appears to belie ostracoderm extinction and demise rather than competition with jawed vertebrates.

scholarly journals Is evolutionary history repeatedly rewritten in light of new fossil discoveries?

2010 ◽  
Vol 278 (1705) ◽  
pp. 599-604 ◽  
Author(s):  
J. E. Tarver ◽  
P. C. J. Donoghue ◽  
M. J. Benton
Keyword(s):  
New Species ◽  
Mass Media ◽  
Fossil Record ◽  
Evolutionary History ◽  
Popular Science ◽  
Old World Monkeys ◽  
Catarrhine Primates ◽  
The Past ◽  
Fossil Records ◽  
Species Being

Mass media and popular science journals commonly report that new fossil discoveries have ‘rewritten evolutionary history’. Is this merely journalistic hyperbole or is our sampling of systematic diversity so limited that attempts to derive evolutionary history from these datasets are premature? We use two exemplars—catarrhine primates (Old World monkeys and apes) and non-avian dinosaurs—to investigate how the maturity of datasets can be assessed. Both groups have been intensively studied over the past 200 years and so should represent pinnacles in our knowledge of vertebrate systematic diversity. We test the maturity of these datasets by assessing the completeness of their fossil records, their susceptibility to changes in macroevolutionary hypotheses and the balance of their phylogenies through study time. Catarrhines have shown prolonged stability, with discoveries of new species being evenly distributed across the phylogeny, and thus have had little impact on our understanding of their fossil record, diversification and evolution. The reverse is true for dinosaurs, where the addition of new species has been non-random and, consequentially, their fossil record, tree shape and our understanding of their diversification is rapidly changing. The conclusions derived from these analyses are relevant more generally: the maturity of systematic datasets can and should be assessed before they are exploited to derive grand macroevolutionary hypotheses.

scholarly journals A stem delphinidan from the Caribbean region of Venezuela

2021 ◽  
Vol 140 (1) ◽  
Author(s):  
Aldo Benites-Palomino ◽  
Andres E. Reyes-Cespedes ◽  
Gabriel Aguirre-Fernández ◽  
Rodolfo Sánchez ◽  
Jorge D. Carrillo-Briceño ◽  
...  
Keyword(s):  
Fossil Record ◽  
Middle Miocene ◽  
Phylogenetic Analyses ◽  
Eastern Pacific ◽  
Caribbean Region ◽  
Taxonomic Identification ◽  
Temporal Fossa ◽  
Northern Atlantic ◽  
The Caribbean ◽  
Phylogenetic Affinities

AbstractThe dense Miocene record of cetaceans is known from localities along the coasts of all continents, mostly in the northern Atlantic or the eastern Pacific regions, but Antarctica. Fossils from the Caribbean region are few and include of a couple of findings from Panama and Venezuela. Here, we report a partly complete skull from the Caujarao Formation (middle Miocene), Falcon State, Caribbean region of Venezuela. Our phylogenetic analyses indicate that the Caujarao specimen is a ‘stem delphinidan’, a group that includes several taxa of early diverging odontocetes whose phylogenetic affinities remain a matter of debate. The fossil record has shown that this group of stem delphinidans was taxonomically diverse, but displayed a somewhat homogeneous cranial patterning, with most of the variations being found within the mandible or tympanoperiotic characters. As other stem delphinidans the Caujarao odontocete displays an enlarged temporal fossa and a fairly symmetrical cranium. Because the skull is missing several key diagnostic characters due to the preservation state of the specimen, a more precise taxonomic identification is not possible. Despite this, the finding of this specimen highlights the importance of the fossil record from the Neogene of Venezuela, and the importance of the area to understand cetacean evolution in the proto-Caribbean.

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.

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