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.

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

Tree-kangaroos of the genus Dendrolagus occupy forest habitats of New Guinea and extreme northeastern Australia, but their evolutionary history is poorly known. Descriptions in the 2000s of near-complete Pleistocene skeletons belonging to larger-bodied species in the now-extinct genus Bohra broadened our understanding of morphological variation in the group and have since helped us to identify unassigned fossils in museum collections, as well as to reassign species previously placed in other genera. Here we describe these fossils and analyse tree-kangaroo systematics via comparative osteology. Including B. planei sp. nov., B. bandharr comb. nov. and B. bila comb. nov., we recognise the existence of at least seven late Cenozoic species of Bohra, with a maximum of three in any one assemblage. All tree-kangaroos (Dendrolagina subtribe nov.) exhibit skeletal adaptations reflective of greater joint flexibility and manoeuvrability, particularly in the hindlimb, compared with other macropodids. The Pliocene species of Bohra retained the stepped calcaneocuboid articulation characteristic of ground-dwelling macropodids, but this became smoothed to allow greater hindfoot rotation in the later species of Bohra and in Dendrolagus. Tree-kangaroo diversification may have been tied to the expansion of forest habitats in the early Pliocene. Following the onset of late Pliocene aridity, some tree-kangaroo species took advantage of the consequent spread of more open habitats, becoming among the largest late Cenozoic tree-dwellers on the continent. Arboreal Old World primates and late Quaternary lemurs may be the closest ecological analogues to the species of Bohra.

The prevention of pregnancy is desirable for female cattle destined for sale in the northern Australian rangelands for both economic and welfare reasons. Controlled access to bulls is often not feasible, nor are any non-surgical methods currently available. Many females are therefore surgically spayed. This study describes a technique for uterine tube resection (UTR), which leaves the ovaries intact and is performed using a vaginal approach, and compares the outcomes from 70 Brahman cows subjected to the procedure with 60 heifers spayed using the dropped ovary technique. The animals were monitored for 10 days following the surgery. There were no mortalities, and two animals were treated for illnesses after the UTRs and recovered. The animals subjected to both surgical procedures showed signs of pelvic discomfort and mild inflammation during recovery. The cows gained an average of 9.3 kg (SD 14.5 kg) of weight over the 10 days of the study compared to the spayed heifers, which lost 3.5 kg (SD 13.3 kg), with 19 and 63% of the animals in each of the groups losing weight, respectively. Uterine tube resection can be considered as a viable alternative to surgical spaying.

Escaping from predators is fundamental for the survival of any prey species. Australian fauna within the 'critical weight range' (CWR; 35 g-5.5 kg) are vulnerable to introduced eutherian predators. The absence of co-evolution between native marsupials and these novel predators may suggest that their antipredator behaviour towards the hunting strategies of these predators is inappropriate or ineffective. We quantified the escape behaviour of eight CWR marsupial taxa (three quadrupedal bandicoots and five bipedal macropods) to determine if differences in how they escape from predators indicate their ability to respond appropriately and effectively to introduced predators. Animals were filmed escaping through a runway and 20 measures relating to their gait, speed and path characteristics were recorded. These were reduced to four dimensions using multidimensional scaling (MDS): MDS1 linear speed versus agility, MDS2 acceleration style, MDS3 reactivity and MDS4 gait characteristics. We found a strong link between the phylogenetic relatedness of species and their use of linear speed or agility when fleeing (phylogenetic heritability, h(2) = 0.96). Bipedal macropod species used straight-line, fast escapes, which may be suited to escape pursuit predators. The quadrupedal bandicoots had an overall slower escape but were more likely to use sudden changes of direction, which can be successful if pursued by a larger, less mobile predator or where there is sufficient vegetation cover to obstruct pursuit. Repeated exposure increased linear speed (MDS1) and hastened the timing of acceleration (MDS2). The phylogenetic signal for escape speed/straightness suggests specific escape tactics may be constrained by morphology, although animals increased the intensity of their response after repeated exposure, suggesting training could enhance effective antipredator responses.

Functional requirements for different diets have a strong selective pressure leading to convergent adaptations across different groups of mammals. As body size has an influence on many biomechanical and physiological characteristics, it is logical that dietary adaptations often have a strong link to body size resulting in observed ‘size guilds’ in many diverse phylogenetic lineages. However, non-allometric variation in skull shape may provide an alternative pathway for species to adapt to diets or prey handling by breaking the mould away from the line of least evolutionary resistance, increased body size. We investigated the relationships between cranial shape and body size in the evolutionary context of the shift from insectivory to hypercarnivory in a monophyletic group of 16 dasyurine marsupial species. Analysis of 35 Procrustes-corrected 3D skull landmarks revealed that overall, there was a correlation between mean skull shape and size that correlated with diet. However, the dominant shape variation (almost 80% irrespective of phylogeny, and more than 90% when constrained by phylogeny) was not size-related. This non-allometric pattern of skull shape reveals adaptation for different feeding strategies that is independent of absolute size. This highlights the potential for specific ‘thresholds’ in size and shape to exist that have the potential to mark shifts from one dietary niche to the next, that might be applied to the evolution of carnivorous taxa from other lineages.