Natalie Warburton

Myological reconstruction provides valuable information about functional anatomy, ecology, evolution and artistic restoration of extinct taxa. We propose regression-based methods built from a large osteo-myological dataset of extant herbivorous mammals to quantitatively reconstruct absolute masses and relative sizes of masticatory muscles. We used linear and geometric morphometrics variables to calculate equations and predictive errors. The mean predictive errors were acceptable in total sampled equations and remarkably low for specific morphotypes equations. We tested the methods on six disparate and challenging extinct taxa. The reconstructed myological features can be used to improve or complement other approaches, such as digital modeling. In most cases, the selected fossils obtained myological proportions similar to those previously proposed, while total masses were smaller in several cases. Inferences for fossils yielded similarities to a phylogenetically diverse sample of living species, but also identified unique traits. Archaeotherium, Diprotodon, and Megaladapis can be interpreted as possessing generalized, not markedly derived myological configurations. Telicomys was reconstructed as possessing muscles larger than all extant rodents but similar proportions to extant caviid caviomorphs. Paedotherium and Argyrolagus were reconstructed as possessing total masticatory masses similar to extant rodents. They also present myological proportions that partially resemble potoroids, sciuromorphs, and myomorphs, but also reveal unique traits for each of them, so they would represent exclusively extinct morphotypes. The here proposed quantitative, statistically-based tools will be useful for future researchers to infer muscle proportions and sizes in extinct taxa, and can be applied to diverse lineages and ecomorphs including those with no extant analogue.

The ‘woylie’ (Bettongia penicillata ogilbyi) is a critically endangered potoroid marsupial from the southwest of Western Australia that has been the focus of conservation efforts over the past few decades. Investigations have focused on methods to improve the conservation of the species, including genetic sampling and mapping to better understand their apparent intraspecific diversity and distribution. Most studies have focused on genetic tools to understand the taxon. However, few studies have used subfossil specimens to inform conservation strategies. Apparently genetically distinct subfossil specimens of woylies on the Nullarbor have previously been proposed to represent a new species. In this investigation we use craniodental morphological characters to assess the validity of this species, as well as review the Bettongia penicillata complex as a whole. This investigation used subfossil, modern and historical specimens from museum collections to ensure the broadest coverage for the taxon. This investigation supports the validity of the previously genetically defined Nullarbor species based on unique morphological characters, which is described and named herein as Bettongia haoucharae sp. nov. Furthermore, our analyses suggest that B. p. ogilbyi should be given full species status. After a thorough redescription of craniodental and some postcranial elements, we established (i) Bettongia ogilbyi ogilbyi comb. nov., (ii) an additional two new subspecies, and (iii) a previously synonymised subspecies within the B. penicillata complex. These results highlight the need for a combined approach to taxonomy, with most of the genetic work on B. penicillata in recent years being restricted to living individuals. Our results reveal that B. penicillata can be considered extinct, B. o. ogilbyi is critically endangered with a single individual in the Kanyana Wildlife Rehabilitation Centre and a wild population in the Tutanning Nature Reserve remaining, B. o. sylvatica is critically endangered but recovering as it has been translocated throughout Australia, and B. o. francisca, and B. o. odontoploica are extinct. Future taxonomic work should aim to combine morphology and molecular work using subfossil, modern and historical specimens for a complete understanding of species.

Among marsupials, the endangered numbat (Myrmecobius fasciatus) is the only obligate myrmecophage with a diet comprised strictly of termites. Like many other specialised myrmecophagous mammals, numbats have a gracile and highly specialised skull morphology with an elongated rostrum and small braincase. Myrmecobiidae is one of four taxonomic families within the Australasian marsupial order Dasyuromorphia, and to date, the muscular anatomy of any member of this group is relatively poorly known. We utilised microdissection and contrast-enhanced microcomputed tomography scanning to provide the first comprehensive qualitative and quantitative descriptions of jaw muscle anatomy in numbats and quolls (Dasuyrus species). The arrangement of the jaw muscles across these species was conservative, both in gross anatomy and muscle proportions, corresponding to a 'generalised' mammalian pattern. In contrast to Dasyurus, the jaw muscles of the numbat were greatly reduced. Many aspects of the muscle anatomy of the numbat were similar to patterns reported in other myrmecophagous species, particularly a greatly reduced temporalis muscle. Unusually, the digastric muscle in the numbat was comprised of a single, large anterior belly while the posterior belly was absent. We propose that the enlarged anterior belly of the digastric may be linked to jaw stabilisation and coordination of tongue movements during feeding. The lateral insertion and fascial connection of the digastric to the tongue in numbats may also aid in distributing stress evenly across the jaw and minimise muscle fatigue. The muscle descriptions and three-dimensional models provided in this study will facilitate further analysis of musculoskeletal adaptation and evolution within the Dasyuromorphia.

Monotremes embody many unique aspects of mammalian evolution, and their skeletal anatomy presents features that differ markedly from the placental mammals that dominate comparative anatomy texts.

The creation of this skeletal atlas short-beaked echidna (Tachyglossus aculeatus) has been guided by the recognition of a need for a comprehensive anatomical reference that can serve as a resource for researchers across fields including veterinary, comparative anatomy, conservation biology, and palaeontology.

Mammalian skeletal systems are characterised by a range of specialised traits reflecting their distinct evolutionary lineages and ecological niches. The echidna's skeleton features a characteristic sprawling gait, reptilian-likepectoral girdle and forelimbs that are specialised for their particular mode of humeral-rotation digging. These characteristics, coupled with the limited availability of anatomical resources for the taxa, make this atlas a valuable resource for anyone engaged in the study of biological form and function.

We present a new taxonomic study of fossil giraffids from the Siwaliks of Pakistan. The recovered material belongs to the family Giraffidae and includes a cranium of Vishnutherium priscillum, maxillary isolated cheek teeth of Bramatherium grande, maxillary isolated cheek teeth and mandibular fragments of Bramatherium megacephalum. These specimens were collected from the localities of Dhok Bun Ameer Khatoon, Chakwal district, and Hasnot, Jhelum district, Punjab, Pakistan. These outcrops belong to the Chinji Formation and Dhok Pathan Formation, respectively, of lower to middle Siwaliks, dated as Middle to Late Miocene in age. The presence of fossil fauna that primarily fed on herbaceous, grassy, and bushy vegetation suggests that both Dhok Bun Ameer Khatoon and Hasnot were dominated by mixed woodland habitats. These localities have a very rich fossil fauna and the cranium of Vishnutherium priscillum is the first that has been reported from Dhok Bun Ameer Khatoon.

This is a correction to: Marcos D Ercoli, Alicia Álvarez, Natalie M Warburton, Christine M Janis, Elena G Potapova, Susan W Herring, Guillermo H Cassini, Juliana Tarquini, Alexander Kuznetsov, Myology of the masticatory apparatus of herbivorous mammals and a novel classification for a better understanding of herbivore diversity, Zoological Journal of the Linnean Society, Volume 198, Issue 4, August 2023, Pages 1106–1155, https://doi.org/10.1093/zoolinnean/zlac102

In the originally published version of the supplementary data file for this manuscript, the preservation method and the name of muscles were erroneous for some specimens. These errors have been corrected. The corrections do not have implication