Anusuya Chinsamy-Turan

Paleobiological implications of the bone histology of the extinct Australian marsupial Nimbadon lavarackorum

Publisher: Cambridge University Press (CUP)

Date: 05-2023

DOI: 10.1017/JPA.2023.22

Abstract: Despite the recognition that bone histology provides much information about the life history and biology of extinct animals, osteohistology of extinct marsupials is sorely lacking. We studied the bone histology of the ca. 15-million-year-old Nimbadon lavarackorum from Australia to obtain insight into its biology. The histology of thin sections of five femora and five tibiae of juveniles, subadult, and adult Nimbadon lavarackorum was studied. Growth marks in the bones suggest that N . lavarackorum took at least 7–8 years (and likely longer) to reach skeletal maturity. The predominant bone tissue during early ontogeny is parallel-fibered bone, whereas an even slower rate of bone formation is indicated by the presence of lamellar bone tissue in the periosteal parts of the compacta in older in iduals. Deposition of bone was interrupted periodically by lines of arrested growth or annuli. This cyclical growth strategy indicates that growth in N . lavarackorum was affected by the prevailing environmental conditions and available resources, as well as seasonal physiological factors such as decreasing body temperatures and metabolic rates.

Histovariability and Palaeobiological Implications of the Bone Histology of the Dromornithid, Genyornis newtoni

Publisher: MDPI AG

Date: 20-05-2021

DOI: 10.3390/D13050219

Abstract: The bone microstructure of extinct animals provides a host of information about their biology. Although the giant flightless dromornithid, Genyornis newtoni, is reasonably well known from the Pleistocene of Australia (until its extinction about 50–40 Ka), aside from various aspects of its skeletal anatomy and taxonomy, not much is known about its biology. The current study investigated the histology of fifteen long bones of Genyornis (tibiotarsi, tarsometatarsi and femora) to deduce information about its growth dynamics and life history. Thin sections of the bones were prepared using standard methods, and the histology of the bones was studied under normal and polarised light microscopy. Our histological analyses showed that Genyornis took more than a single year to reach sexual maturity, and that it continued to deposit bone within the OCL for several years thereafter until skeletal maturity was attained. Thus, sexual maturity and skeletal maturity were asynchronous, with the former preceding the latter. Our results further indicated that Genyornis responded to prevailing environmental conditions, which suggests that it retained a plesiomorphic, flexible growth strategy. Additionally, our analyses of the three long bones showed that the tibiotarsus preserved the best record of growth for Genyornis.

Ontogenetic growth and the development of a unique fibrocartilage entheses in Macropus fuliginosus

Publisher: Elsevier BV

Date: 02-2021

DOI: 10.1016/J.ZOOL.2020.125860

ACCEPTING EVOLUTION

Publisher: Wiley

Date: 17-10-2007

DOI: 10.1111/J.1558-5646.2007.00276.X

Abstract: Poor public perceptions and understanding of evolution are not unique to the developed and more industrialized nations of the world. International resistance to the science of evolutionary biology appears to be driven by both proponents of intelligent design and perceived incompatibilities between evolution and a ersity of religious faiths. We assessed the success of a first-year evolution course at the University of Cape Town and discovered no statistically significant change in the views of students before the evolution course and thereafter, for questions that challenged religious ideologies about creation, bio ersity, and intelligent design. Given that students only appreciably changed their views when presented with "facts," we suggest that teaching approaches that focus on providing ex les of experimental evolutionary studies, and a strong emphasis on the scientific method of inquiry, are likely to achieve greater success. This study also reiterates the importance of engaging with students' prior conceptions, and makes suggestions for improving an understanding and appreciation of evolutionary biology in countries such as South Africa with an inadequate secondary science education system, and a dire lack of public engagement with issues in science.

Osteohistology of Dromornis stirtoni (Aves: Dromornithidae) and the biological implications of the bone histology of the Australian mihirung birds

Publisher: Wiley

Date: 17-08-2023

DOI: 10.1002/AR.25047

Abstract: The late Miocene Dromornis stirtoni is the largest of the giant flightless dromornithid birds. Here, we studied 22 long bones (femora, tibiotarsi, tarsometatarsi) of D. stirtoni to assess its osteohistology to deduce various aspects of its life history. Our results show that D. stirtoni took several years (likely, more than a decade), to reach adult body size, after which its growth rate slowed down, and skeletal maturity occurred. This growth strategy differs from that of its Pleistocene relative, Genyornis newtoni , which experienced faster rates of growth to reach adult body size. We propose that these mihirung birds, separated by millions of years, each responded to the prevailing environmental conditions of the time, by selecting for different growth strategies, with D. stirtoni having an extreme K‐selected life history strategy. The presence of medullary bone permitted the identification of female D. stirtoni specimens, and its presence in some bones lacking an OCL layer showed sexual maturity preceded its formation. We postulate that while G. newtoni had a somewhat greater reproductive potential than D. stirtoni , it remained far less than that observed in the extant emu ( Dromaius novaehollandiae ). Genyornis newtoni survived into the late Pleistocene alongside extant emus and overlapped the arrival of the first humans in Australia, but the former species shortly thereafter became extinct while emus remain prolific.

Sexual dimorphism in the late Miocene mihirungDromornis stirtoni(Aves: Dromornithidae) from the Alcoota Local Fauna of central Australia

Publisher: Informa UK Limited

Date: 07-06-2016

DOI: 10.1080/02724634.2016.1180298

Postnatal development of the largest subterranean mammal (Bathyergus suillus): Morphology, osteogenesis, and modularity of the appendicular skeleton

Publisher: Wiley

Date: 08-2019

DOI: 10.1002/DVDY.81

Abstract: Subterranean mammals show a suite of musculoskeletal adaptations that enables efficient digging. However, little is known about their development. We assessed ontogenetic changes in functionally relevant skeletal traits, and ossification patterns (periosteal and endochondral bone modules) in a truly subterranean scratch-digging rodent, Bathyergus. We studied 52 in iduals (202 long bones) from a wild population by using a multiscale approach involving internal and external morphology. Multivariate analysis showed significant morphological changes during ontogeny. A specialized phenotype is expressed perinatally (eg, greater external robustness and developed olecranon, teres major, and deltoid processes), whereas adults presented slender bones with significantly thicker cross-sections. Ossification modules scaled mostly isometrically with body size parameters. Periosteal modules showed high variability and tended to grow faster than endochondral modules. Scratch-digging adaptations appear at perinatal age and then specialize in subadults. Early development of agonistic and digging behaviors and onset of sexual maturation seems to contribute to its development, although genetic factors also seem to play an important role. Ontogenetic differences are probably a trade-off to counteract weaker cortical bone properties and poor muscle development in juveniles, whereas slender but thicker cortical bones maximize bone resistance during burrow construction without compromising locomotor performance in adults.

Variation of the outer circumferential layer in the limb bones of birds

Publisher: Museum and Institute of Zoology at the Polish Academy of Sciences

Date: 12-2004

DOI: 10.3161/068.039.0210

University Of Cape Town Faculty Of Science

Location: South Africa

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University Of The Witwatersrand Faculty Of Science

Location: South Africa

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Iziko South African Museum

Location: South Africa

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Discovery Projects - Grant ID: DP180101913

Start Date: 2018

End Date: 12-2022

Amount: $416,584.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP190103636

Start Date: 04-2019

End Date: 04-2022

Amount: $445,000.00

Funder: Australian Research Council