The stocky skeletons and post-cranial anatomy of many extinct kangaroos indicate that they might ... more The stocky skeletons and post-cranial anatomy of many extinct kangaroos indicate that they might have engaged in varied locomotor behaviors, rather than bipedal hopping, as their primary mode of locomotion. This study investigates support for this idea by estimating femoral bone perfusion, which is a correlate of locomotor intensity, in extinct kangaroos compared to living hopping species. Femur blood flow rates can be estimated from the sizes of nutrient foramina on the femur shaft of living and extinct species, without preservation of soft tissue. Estimated femur blood flow rates among the extinct Macropus, Protemnodon and Sthenurinae (Sthenurus, Simosthenurus and Procoptodon) are not significantly different from one another but are significantly greater than in living hopping macropods after accounting for the effect of body mass, consistent with their purportedly different locomotor style. The giant sthenurines have more robust femora than extrapolated from data of living hopping macropods, possibly due to the larger sthenurines requiring relatively stronger leg bones to support their heavier body weights, especially if loaded onto a single limb during bipedal striding.
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
JOURNAL OF QUATERNARY SCIENCE (2001) 16 (1) 4959 Copyright 2001 John Wiley & Sons, Ltd. ..... more JOURNAL OF QUATERNARY SCIENCE (2001) 16 (1) 4959 Copyright 2001 John Wiley & Sons, Ltd. ... Electron spin resonance dating of the fossil ... RAINER GRU¨ N1*, KEVIN MORIARTY2 and ROD WELLS3 1Research School of Earth Sciences, The Australian National ...
The timing of the extinction of the Australian Megafauna and whether it was simultaneous and wide... more The timing of the extinction of the Australian Megafauna and whether it was simultaneous and widespread has been a much researched topic in Quaternary geoscience. The Black Creek Swamp Megafauna site on Kangaroo Island was thought to be a refugium for Megafauna; however, recent and multidiscipline age determinations have established that the fossils are considerably older than the well-quoted extinction age of 45 kyr. Further radiocarbon age determinations, d 13 C isotope analysis and 13 C-NMR spectroscopy of the fossil containing organic matter demonstrates that it is highly soluble and accumulated as recently as 31-18 cal. kyr BP. These radiocarbon ages are much younger than the 100-50 kyr age bracket ascertained for the fossil material itself, implying separate episodes of death, deposition and burial. The soluble nature of the organic matter and increasing radiocarbon ages with depth suggests lateral accumulation, probably transported by subsurface waters from elevated areas proximal to the low-lying swamp. Such depositional conditions and 14 C age range implies that the site may have experienced an unusually wet Last Glacial Maximum, due maybe to its proximity to the continental shelf and thus to maritime conditions. C3 vegetation dominates the Black Creek Swamp and its organic matter (d 13 C; À30% and À23%); however, variations in d 13 C may indicate climatic shifts. 13 C-enrichment and an abundance of salt-tolerant gastropods within the site's final phase of sediment accumulation (o6 cal. kyr BP) suggest that conditions during this most recent period were not as wet as those of the Last Glacial Maximum.
Understanding the causes and consequences of biases in the sex ratio at birth and of adults in sp... more Understanding the causes and consequences of biases in the sex ratio at birth and of adults in species of mammals that have unusual life histories may help us know whether sex ratios are adaptive responses to ecological and evolutionary forces and may be important in conserving endangered species. For example, have sex ratio biases at birth and in adults in species of mammals evolved as an adaptive response to environmental unpredictability? We investigated the sex ratio of populations of hairy-nosed wombats, Lasiorhinus latifrons, and the endangered Lasiorhinus krefftii. The social structure of Lasiorhinus includes male philopatry and female dispersal, which are unusual traits among mammals. Reproduction in these wombats is often curtailed by unpredictable droughts, and so wombats may be a suitable target group for understanding the causes and consequences of biases in mammalian sex ratios. The sex ratio in populations of adult L. latifrons reported in the scientific literature varied widely, but the mean percentage of females in the 10 studies examined was 54.9 with a 95% confidence interval of 50.3 to 59.5. In the population of L. latifrons that we monitored for nearly twenty years beginning in 1994, the percentage of adult females varied between 66 and 37% in a manner that suggested homeostasis. The growth of the population of critically endangered L. krefftii from 52 males and 29 females in 2000 to 79 males and 91 females in 2016 suggested that more females than males were born. The sex ratio of pouch young of L. latifrons was biased towards females at times. The mean percentage of female pouch young in 19 breeding seasons was 56.4 (95% confidence interval of 50.4-62.4). Variation in the sex ratio of pouch young was examined regarding theories of sex allocation. When the percentage of adult females in the population was lower (37-50%) and had been declining, L. latifrons mothers had more female than male pouch young, but the sex ratio of pouch young was about equal when the percentage of adult females was higher (53-66%). This pattern is partly consistent with Fisher's principle, which is also known as the homeostatic hypothesis (HH). When the percentage of adult females was lower, the mothers of female pouch young were in better condition than the mothers of male pouch young, which is consistent with a reversed Trivers-Willard (TW) effect in part. The biases in the sex ratio of adult and pouch young wombats may be adaptive responses to their life history and to demographic and environmental cues. Significance statement Wombats are unusual among mammals in that males are philopatric and females disperse. Hairy-nosed wombats (two species within the genus Lasiorhinus) exist tenuously in semi-arid environments because of infrequent reproduction, habitat degradation, and drought. L. krefftii is critically endangered. This study suggests that following severe droughts, a female bias in the sex ratio of pouch young and of adults may result in populations increasing more rapidly than if the sex ratio was equal. Agencies charged with managing and conserving wombats could make use of this knowledge by undertaking more comprehensive demographic Communicated by K. Eva Ruckstuhl
PATE, FD, MCDOWELL, MC, WELLS, RT & SMITH, AM, 2006. Additional AMS radiocarbon d... more PATE, FD, MCDOWELL, MC, WELLS, RT & SMITH, AM, 2006. Additional AMS radiocarbon dates for Wet Cave and the timing of megafaunal extinctions in the Naracoorte region of South Australia. Alcheringa Special Issue 1, 277-279. ISBN 0 9757894 5 7.
The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian co... more The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian continent from the late Oligocene through to their extinction in the Late Pleistocene. The group is known for their odd 'tapir-like' crania and distinctive clawed forelimbs, but their appendicular anatomy has never been formally described. We provide the first descriptions of the appendicular skeleton and body mass estimates for three palorchestid species, presenting newly-identified, and in some cases associated, material of mid-Miocene Propalorchestes, Plio-Pleistocene Palorchestes parvus and Pleistocene Palorchestes azael alongside detailed comparisons with extant and fossil vombatiform marsupials. We propose postcranial diagnostic characters at the family, genus and species level. Specialisation in the palorchestid appendicular skeleton evidently occurred much later than in the cranium and instead correlates with increasing body size within the lineage. We conclude that palorchestid forelimbs were highly specialised for the manipulation of their environment in the acquisition of browse, and that they may have adopted bipedal postures to feed. Our results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1000 kg. Additionally, we show that P. azael exhibits some of the most unusual forelimb morphology of any mammal, with a uniquely fixed humeroulnar joint unlike any of their marsupial kin, living or extinct.
... Richard H. Tedford [tedford@amnh.org],Department of Vertebrate Paleontology, American Museum ... more ... Richard H. Tedford [tedford@amnh.org],Department of Vertebrate Paleontology, American Museum of Natural History, New York, NY 10024, USA, Rod T. Wells, School of ... Terrestrial climate in Australia moved toward cool-dry winters by the end of the Pliocene (Gallagher et al. ...
This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba For... more This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba Formation in the soothem Frome Embayment (Tarkarooloo Basin), South Australia. The Duvio-Iacustrine Namba Formation can be divided into two informal members based on regional lithological changes. The lower member bears Balcombian-Batesfordian (medial Miocene) pollen floras representing subtropical rainforest and adjacent savanna habitats. The top of the lower member yields the PIopa Fauna of aquatic and terrestrial vertebrates including fish, turtles, crocodiles, two genera of dasyurids and seven genera of diprotodontan marsupials and a platanistid porpoise. The base of the upper member contains a similar vertebrate fauna (Ericmas Fauna) bot includes a platypus and, significantly, diprotodontid marsupials which are the dominant large mammals in the contemporaneous Ngapakaldi Fauna of the Lake Eyre basin.
Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on... more Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14 C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45-75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14 C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the high organic matter contents of approximately 8%, has implications for the age of the megafauna buried in this layer. The overlying modern soil, with its much younger date, contains lower levels of organic matter (3-7%) and gastropods not seen in the fossil layer. This suggests a substantial change in environmental conditions probably due to an alteration in the floodplain drainage conditions. This chronological and sedimentalogical discontinuity indicates that 2 distinct depositional regimes existed and were separated by up to 10,000 14 C yr. A calcareous, sandy silt deposit underlying the fossil layer is a calcarenite deposit with low total organic content and is considered the base of the section; it suggests a third separate depositional episode. As such, the Black Creek Swamp in the southwest corner of Kangaroo Island formed intermittently over at least the last 20,000 yr during 3 distinct depositional phases, one of which was the formation of the fossil-laden, organic-rich floodplain surface, which has a possible minimum age of approximately 15,000 to 19,000 BP.
<p>Dorsal view of the cervical (dark grey), thoracic (white) and lumbar (light grey) verteb... more <p>Dorsal view of the cervical (dark grey), thoracic (white) and lumbar (light grey) vertebral columns of (A) <i>T</i>. <i>carnifex</i>; (B) <i>P</i>. <i>cinereus</i>; (C) <i>L</i>. <i>latifrons</i>; (D) <i>Tri</i>. <i>vulpecula</i>; (E) <i>M</i>. <i>rufus</i>; (F) <i>D</i>. <i>viverrinus</i>; (G) <i>S</i>. <i>harrisii</i>; and (H) <i>Thy</i>. <i>cynocephalus</i>. Scale bar equals 100 mm for <i>T</i>. <i>carnifex</i>, other taxa are scaled for proportional comparison. Phylogenetic relationships displayed at bottom of figure are based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0208020#pone.0208020.ref041" target="_blank">41</a>].</p
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial ... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
Using demonstrated relationships between body mass and humeral and femoral circumferences, we cal... more Using demonstrated relationships between body mass and humeral and femoral circumferences, we calculate the weight of the only specimen of Thylacoleo carnifex known from a near-complete skeleton. Body weights of 112–143 kg were estimated for this individual, from Moree, north-western New South Wales. Extrapolating on the basis of geometric similtude, we further estimated the weight of the largest T. carnifex for which we had cranial data at 128–164 kg. Moreover, estimates for at least three of the thirteen available specimens exceeded 124–160 kg, suggesting that individuals of this size were common. Our estimates of average weight for the species range from 101 to 130 kg. These results clearly show that Pleistocene Australia had a 'large' cat equivalent and that 'large' terrestrial predator niches were not then occupied exclusively by reptiles.They may also diminish the argument that soil-nutrient deficiency constrained the evolution of large mammalian carnivores on ...
Alcheringa: An Australasian Journal of Palaeontology, 2006
PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon d... more PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon dates for Wet Cave and the timing of megafaunal extinctions in the Naracoorte region of South Australia. Alcheringa Special Issue 1, 277-279. ISBN 0 9757894 5 7.
<p>(A-D) Comparisons between the vertebral columns of <i>T</i>. <i>carnif... more <p>(A-D) Comparisons between the vertebral columns of <i>T</i>. <i>carnifex</i> and <i>S</i>. <i>harrisii</i>. (A) Assembled vertebral column of <i>T</i>. <i>carnifex</i> (WAM 02.7.2) with tail in natural position based on orientation of articular facets; (B) with tail ventrally flexed; (C) compared with the nearest extant morphological analogue <i>S</i>. <i>harrisii</i> traced from x-ray [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0208020#pone.0208020.ref011" target="_blank">11</a>]; (D) <i>S</i>. <i>harrisii</i> vertebral column from Tasmanian Museum mounted skeleton (grey bars represent the orientation of the pelvis relative to the vertebral column, A-D have all been scaled to the same size for comparative purposes, note the dorso-ventral flexion of the cervical-thoracic column and rigid lumbar, sacral and proximal caudal region); (E) articulated thoraco-lumbar region of <i>T</i>. <i>carnifex</i> as preserved in SAMA P43221 (scale bar equals 50 mm); (F) pathologies on thoracic vertebrae 1/2, 6/7 & 8 of <i>T</i>. <i>carnifex</i> WAM 02.7.2 (scale bar equals 50 mm, note the fusion of the of T1/2 centra possibly the result of calcification of tendons, erosional damage at interface of T6/7 and lipping of the ventral anterior aspect of T8); the tail of <i>T</i>. <i>carnifex</i> assembled (WAM 02.7.2) (G) ventral view, (H) dorsal view (the sacrum comprising four fused vertebrae is followed by three forms of caudal vertebrae (i) proximal nos. 1–6 (ii) transitional no. 7 (iii) distal nos. 8–16., remaining 5 distal caudals in the series omitted, (scale bar equals 100 mm); (I) the tail of <i>T</i>. <i>carnifex</i> showing maximum extent of dorsal flexion in proximal caudal vertebrae (arrow indicates transitional vertebra caudal 7[, scale bar equals 100 mm); and (J) chevron bones collected in the vicinity of the tail of WAM 02.7.1 (scale bar equals 100 mm).</p
This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba For... more This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba Formation in the soothem Frome Embayment (Tarkarooloo Basin), South Australia. The Duvio-Iacustrine Namba Formation can be divided into two informal members based on regional lithological changes. The lower member bears Balcombian-Batesfordian (medial Miocene) pollen floras representing subtropical rainforest and adjacent savanna habitats. The top of the lower member yields the PIopa Fauna of aquatic and terrestrial vertebrates including fish, turtles, crocodiles, two genera of dasyurids and seven genera of diprotodontan marsupials and a platanistid porpoise. The base of the upper member contains a similar vertebrate fauna (Ericmas Fauna) bot includes a platypus and, significantly, diprotodontid marsupials which are the dominant large mammals in the contemporaneous Ngapakaldi Fauna of the Lake Eyre basin.
Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on... more Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45–75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the h...
The stocky skeletons and post-cranial anatomy of many extinct kangaroos indicate that they might ... more The stocky skeletons and post-cranial anatomy of many extinct kangaroos indicate that they might have engaged in varied locomotor behaviors, rather than bipedal hopping, as their primary mode of locomotion. This study investigates support for this idea by estimating femoral bone perfusion, which is a correlate of locomotor intensity, in extinct kangaroos compared to living hopping species. Femur blood flow rates can be estimated from the sizes of nutrient foramina on the femur shaft of living and extinct species, without preservation of soft tissue. Estimated femur blood flow rates among the extinct Macropus, Protemnodon and Sthenurinae (Sthenurus, Simosthenurus and Procoptodon) are not significantly different from one another but are significantly greater than in living hopping macropods after accounting for the effect of body mass, consistent with their purportedly different locomotor style. The giant sthenurines have more robust femora than extrapolated from data of living hopping macropods, possibly due to the larger sthenurines requiring relatively stronger leg bones to support their heavier body weights, especially if loaded onto a single limb during bipedal striding.
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
JOURNAL OF QUATERNARY SCIENCE (2001) 16 (1) 4959 Copyright 2001 John Wiley & Sons, Ltd. ..... more JOURNAL OF QUATERNARY SCIENCE (2001) 16 (1) 4959 Copyright 2001 John Wiley & Sons, Ltd. ... Electron spin resonance dating of the fossil ... RAINER GRU¨ N1*, KEVIN MORIARTY2 and ROD WELLS3 1Research School of Earth Sciences, The Australian National ...
The timing of the extinction of the Australian Megafauna and whether it was simultaneous and wide... more The timing of the extinction of the Australian Megafauna and whether it was simultaneous and widespread has been a much researched topic in Quaternary geoscience. The Black Creek Swamp Megafauna site on Kangaroo Island was thought to be a refugium for Megafauna; however, recent and multidiscipline age determinations have established that the fossils are considerably older than the well-quoted extinction age of 45 kyr. Further radiocarbon age determinations, d 13 C isotope analysis and 13 C-NMR spectroscopy of the fossil containing organic matter demonstrates that it is highly soluble and accumulated as recently as 31-18 cal. kyr BP. These radiocarbon ages are much younger than the 100-50 kyr age bracket ascertained for the fossil material itself, implying separate episodes of death, deposition and burial. The soluble nature of the organic matter and increasing radiocarbon ages with depth suggests lateral accumulation, probably transported by subsurface waters from elevated areas proximal to the low-lying swamp. Such depositional conditions and 14 C age range implies that the site may have experienced an unusually wet Last Glacial Maximum, due maybe to its proximity to the continental shelf and thus to maritime conditions. C3 vegetation dominates the Black Creek Swamp and its organic matter (d 13 C; À30% and À23%); however, variations in d 13 C may indicate climatic shifts. 13 C-enrichment and an abundance of salt-tolerant gastropods within the site's final phase of sediment accumulation (o6 cal. kyr BP) suggest that conditions during this most recent period were not as wet as those of the Last Glacial Maximum.
Understanding the causes and consequences of biases in the sex ratio at birth and of adults in sp... more Understanding the causes and consequences of biases in the sex ratio at birth and of adults in species of mammals that have unusual life histories may help us know whether sex ratios are adaptive responses to ecological and evolutionary forces and may be important in conserving endangered species. For example, have sex ratio biases at birth and in adults in species of mammals evolved as an adaptive response to environmental unpredictability? We investigated the sex ratio of populations of hairy-nosed wombats, Lasiorhinus latifrons, and the endangered Lasiorhinus krefftii. The social structure of Lasiorhinus includes male philopatry and female dispersal, which are unusual traits among mammals. Reproduction in these wombats is often curtailed by unpredictable droughts, and so wombats may be a suitable target group for understanding the causes and consequences of biases in mammalian sex ratios. The sex ratio in populations of adult L. latifrons reported in the scientific literature varied widely, but the mean percentage of females in the 10 studies examined was 54.9 with a 95% confidence interval of 50.3 to 59.5. In the population of L. latifrons that we monitored for nearly twenty years beginning in 1994, the percentage of adult females varied between 66 and 37% in a manner that suggested homeostasis. The growth of the population of critically endangered L. krefftii from 52 males and 29 females in 2000 to 79 males and 91 females in 2016 suggested that more females than males were born. The sex ratio of pouch young of L. latifrons was biased towards females at times. The mean percentage of female pouch young in 19 breeding seasons was 56.4 (95% confidence interval of 50.4-62.4). Variation in the sex ratio of pouch young was examined regarding theories of sex allocation. When the percentage of adult females in the population was lower (37-50%) and had been declining, L. latifrons mothers had more female than male pouch young, but the sex ratio of pouch young was about equal when the percentage of adult females was higher (53-66%). This pattern is partly consistent with Fisher's principle, which is also known as the homeostatic hypothesis (HH). When the percentage of adult females was lower, the mothers of female pouch young were in better condition than the mothers of male pouch young, which is consistent with a reversed Trivers-Willard (TW) effect in part. The biases in the sex ratio of adult and pouch young wombats may be adaptive responses to their life history and to demographic and environmental cues. Significance statement Wombats are unusual among mammals in that males are philopatric and females disperse. Hairy-nosed wombats (two species within the genus Lasiorhinus) exist tenuously in semi-arid environments because of infrequent reproduction, habitat degradation, and drought. L. krefftii is critically endangered. This study suggests that following severe droughts, a female bias in the sex ratio of pouch young and of adults may result in populations increasing more rapidly than if the sex ratio was equal. Agencies charged with managing and conserving wombats could make use of this knowledge by undertaking more comprehensive demographic Communicated by K. Eva Ruckstuhl
PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon d... more PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon dates for Wet Cave and the timing of megafaunal extinctions in the Naracoorte region of South Australia. Alcheringa Special Issue 1, 277-279. ISBN 0 9757894 5 7.
The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian co... more The Palorchestidae are a family of marsupial megafauna occurring across the eastern Australian continent from the late Oligocene through to their extinction in the Late Pleistocene. The group is known for their odd 'tapir-like' crania and distinctive clawed forelimbs, but their appendicular anatomy has never been formally described. We provide the first descriptions of the appendicular skeleton and body mass estimates for three palorchestid species, presenting newly-identified, and in some cases associated, material of mid-Miocene Propalorchestes, Plio-Pleistocene Palorchestes parvus and Pleistocene Palorchestes azael alongside detailed comparisons with extant and fossil vombatiform marsupials. We propose postcranial diagnostic characters at the family, genus and species level. Specialisation in the palorchestid appendicular skeleton evidently occurred much later than in the cranium and instead correlates with increasing body size within the lineage. We conclude that palorchestid forelimbs were highly specialised for the manipulation of their environment in the acquisition of browse, and that they may have adopted bipedal postures to feed. Our results indicate palorchestids were bigger than previously thought, with the largest species likely weighing over 1000 kg. Additionally, we show that P. azael exhibits some of the most unusual forelimb morphology of any mammal, with a uniquely fixed humeroulnar joint unlike any of their marsupial kin, living or extinct.
... Richard H. Tedford [tedford@amnh.org],Department of Vertebrate Paleontology, American Museum ... more ... Richard H. Tedford [tedford@amnh.org],Department of Vertebrate Paleontology, American Museum of Natural History, New York, NY 10024, USA, Rod T. Wells, School of ... Terrestrial climate in Australia moved toward cool-dry winters by the end of the Pliocene (Gallagher et al. ...
This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba For... more This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba Formation in the soothem Frome Embayment (Tarkarooloo Basin), South Australia. The Duvio-Iacustrine Namba Formation can be divided into two informal members based on regional lithological changes. The lower member bears Balcombian-Batesfordian (medial Miocene) pollen floras representing subtropical rainforest and adjacent savanna habitats. The top of the lower member yields the PIopa Fauna of aquatic and terrestrial vertebrates including fish, turtles, crocodiles, two genera of dasyurids and seven genera of diprotodontan marsupials and a platanistid porpoise. The base of the upper member contains a similar vertebrate fauna (Ericmas Fauna) bot includes a platypus and, significantly, diprotodontid marsupials which are the dominant large mammals in the contemporaneous Ngapakaldi Fauna of the Lake Eyre basin.
Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on... more Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14 C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45-75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14 C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the high organic matter contents of approximately 8%, has implications for the age of the megafauna buried in this layer. The overlying modern soil, with its much younger date, contains lower levels of organic matter (3-7%) and gastropods not seen in the fossil layer. This suggests a substantial change in environmental conditions probably due to an alteration in the floodplain drainage conditions. This chronological and sedimentalogical discontinuity indicates that 2 distinct depositional regimes existed and were separated by up to 10,000 14 C yr. A calcareous, sandy silt deposit underlying the fossil layer is a calcarenite deposit with low total organic content and is considered the base of the section; it suggests a third separate depositional episode. As such, the Black Creek Swamp in the southwest corner of Kangaroo Island formed intermittently over at least the last 20,000 yr during 3 distinct depositional phases, one of which was the formation of the fossil-laden, organic-rich floodplain surface, which has a possible minimum age of approximately 15,000 to 19,000 BP.
<p>Dorsal view of the cervical (dark grey), thoracic (white) and lumbar (light grey) verteb... more <p>Dorsal view of the cervical (dark grey), thoracic (white) and lumbar (light grey) vertebral columns of (A) <i>T</i>. <i>carnifex</i>; (B) <i>P</i>. <i>cinereus</i>; (C) <i>L</i>. <i>latifrons</i>; (D) <i>Tri</i>. <i>vulpecula</i>; (E) <i>M</i>. <i>rufus</i>; (F) <i>D</i>. <i>viverrinus</i>; (G) <i>S</i>. <i>harrisii</i>; and (H) <i>Thy</i>. <i>cynocephalus</i>. Scale bar equals 100 mm for <i>T</i>. <i>carnifex</i>, other taxa are scaled for proportional comparison. Phylogenetic relationships displayed at bottom of figure are based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0208020#pone.0208020.ref041" target="_blank">41</a>].</p
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial ... more This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Des... more The extinct marsupial 'lion' Thylacoleo carnifex was Australia's largest mammalian carnivore. Despite being the topic of more discussion than any other extinct Australian marsupial (excepting perhaps the Thylacine), basic aspects of its palaeobiology, including its locomotory repertoire, remain poorly understood. Recent discoveries allowed the first reconstruction of an entire skeleton including the first complete tail and hitherto-unrecognised clavicles. Here we describe these elements and reassess the biomechanics of the postcranial skeleton via comparisons with a range of extant terrestrial, scansorial and arboreal Australian marsupials. Our analysis suggests that T. carnifex possessed: a relatively stiff tail comprising half of the vertebral column length; proximal caudal centra exhibiting a relatively high resistance to sagittal and lateral bending (RSB and RTB); relatively enlarged areas of origin for caudal flexors and extensors; a rigid lumbar spine; and a shoulder girdle braced by strong clavicles. The lever arms of major muscle/tendon systems controlling the axial and appendicular skeleton were identified and RSB and RTB calculated. The combination of these features compared most closely overall with those of the much smaller Tasmanian Devil (Sarcophilus harrisii), a hunter/scavenger capable of climbing. Similar locomotor behaviour is proposed for Thylacoleo carnifex. Orientation of articular facets and RSB stresses also indicate that T. carnifex may have held its tail in a dorsally-flexed position.
Using demonstrated relationships between body mass and humeral and femoral circumferences, we cal... more Using demonstrated relationships between body mass and humeral and femoral circumferences, we calculate the weight of the only specimen of Thylacoleo carnifex known from a near-complete skeleton. Body weights of 112–143 kg were estimated for this individual, from Moree, north-western New South Wales. Extrapolating on the basis of geometric similtude, we further estimated the weight of the largest T. carnifex for which we had cranial data at 128–164 kg. Moreover, estimates for at least three of the thirteen available specimens exceeded 124–160 kg, suggesting that individuals of this size were common. Our estimates of average weight for the species range from 101 to 130 kg. These results clearly show that Pleistocene Australia had a 'large' cat equivalent and that 'large' terrestrial predator niches were not then occupied exclusively by reptiles.They may also diminish the argument that soil-nutrient deficiency constrained the evolution of large mammalian carnivores on ...
Alcheringa: An Australasian Journal of Palaeontology, 2006
PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon d... more PATE, FD, MCDOWELL, MC, WELLS, RT &amp;amp;amp; SMITH, AM, 2006. Additional AMS radiocarbon dates for Wet Cave and the timing of megafaunal extinctions in the Naracoorte region of South Australia. Alcheringa Special Issue 1, 277-279. ISBN 0 9757894 5 7.
<p>(A-D) Comparisons between the vertebral columns of <i>T</i>. <i>carnif... more <p>(A-D) Comparisons between the vertebral columns of <i>T</i>. <i>carnifex</i> and <i>S</i>. <i>harrisii</i>. (A) Assembled vertebral column of <i>T</i>. <i>carnifex</i> (WAM 02.7.2) with tail in natural position based on orientation of articular facets; (B) with tail ventrally flexed; (C) compared with the nearest extant morphological analogue <i>S</i>. <i>harrisii</i> traced from x-ray [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0208020#pone.0208020.ref011" target="_blank">11</a>]; (D) <i>S</i>. <i>harrisii</i> vertebral column from Tasmanian Museum mounted skeleton (grey bars represent the orientation of the pelvis relative to the vertebral column, A-D have all been scaled to the same size for comparative purposes, note the dorso-ventral flexion of the cervical-thoracic column and rigid lumbar, sacral and proximal caudal region); (E) articulated thoraco-lumbar region of <i>T</i>. <i>carnifex</i> as preserved in SAMA P43221 (scale bar equals 50 mm); (F) pathologies on thoracic vertebrae 1/2, 6/7 & 8 of <i>T</i>. <i>carnifex</i> WAM 02.7.2 (scale bar equals 50 mm, note the fusion of the of T1/2 centra possibly the result of calcification of tendons, erosional damage at interface of T6/7 and lipping of the ventral anterior aspect of T8); the tail of <i>T</i>. <i>carnifex</i> assembled (WAM 02.7.2) (G) ventral view, (H) dorsal view (the sacrum comprising four fused vertebrae is followed by three forms of caudal vertebrae (i) proximal nos. 1–6 (ii) transitional no. 7 (iii) distal nos. 8–16., remaining 5 distal caudals in the series omitted, (scale bar equals 100 mm); (I) the tail of <i>T</i>. <i>carnifex</i> showing maximum extent of dorsal flexion in proximal caudal vertebrae (arrow indicates transitional vertebra caudal 7[, scale bar equals 100 mm); and (J) chevron bones collected in the vicinity of the tail of WAM 02.7.1 (scale bar equals 100 mm).</p
This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba For... more This report announces the discovery of a diverse vertebrate fauna from exposures of the Namba Formation in the soothem Frome Embayment (Tarkarooloo Basin), South Australia. The Duvio-Iacustrine Namba Formation can be divided into two informal members based on regional lithological changes. The lower member bears Balcombian-Batesfordian (medial Miocene) pollen floras representing subtropical rainforest and adjacent savanna habitats. The top of the lower member yields the PIopa Fauna of aquatic and terrestrial vertebrates including fish, turtles, crocodiles, two genera of dasyurids and seven genera of diprotodontan marsupials and a platanistid porpoise. The base of the upper member contains a similar vertebrate fauna (Ericmas Fauna) bot includes a platypus and, significantly, diprotodontid marsupials which are the dominant large mammals in the contemporaneous Ngapakaldi Fauna of the Lake Eyre basin.
Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on... more Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45–75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the h...
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