Mammals from ‘down under’: a multi-gene species-level phylogeny of marsupial mammals (Mammalia, Metatheria)

May‐Collado, Laura J.; Kilpatrick, C. William; Agnarsson, Ingi

doi:10.7717/peerj.805

Cited by 62 publications

(102 citation statements)

References 87 publications

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“…3 and Supplementary Note 3) agrees in most aspects with previous analyses1011, including support for a monophyletic Stagodontidae, in which the early Campanian–early Maastrichtian Eodelphis and the Albian–Cenomanian Pariadens are successive sister taxa to Didelphodon . We fail to recover a monophyletic Australidelphia (dasyurids+ Dromiciops ), in contrast with the weight of previous morphological and molecular phylogenetic studies19, but this might be an artefact of sparse sampling of these clades in our analysis. Placement of Herpetotherium and Mimoperadectes – Peradectes in the crown clade is novel but differs only slightly from previous topologies112021.…”

Section: Resultscontrasting

confidence: 99%

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

et al. 2016

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Marsupial mammal relatives (stem metatherians) from the Mesozoic Era (252–66 million years ago) are mostly known from isolated teeth and fragmentary jaws. Here we report on the first near-complete skull remains of a North American Late Cretaceous metatherian, the stagodontid Didelphodon vorax. Our phylogenetic analysis indicates that marsupials or their closest relatives evolved in North America, as part of a Late Cretaceous diversification of metatherians, and later dispersed to South America. In addition to being the largest known Mesozoic therian mammal (node-based clade of eutherians and metatherians), Didelphodon vorax has a high estimated bite force and other craniomandibular and dental features that suggest it is the earliest known therian to invade a durophagous predator–scavenger niche. Our results broaden the scope of the ecomorphological diversification of Mesozoic mammals to include therian lineages that, in this case, were linked to the origin and evolution of marsupials.

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Section: Resultscontrasting

confidence: 99%

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

et al. 2016

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“…1 a) [Murphy et al, 2001[Murphy et al, , 2004BinindaEmonds et al, 2007], and thus they are the closest living relatives of placental (eutherian) mammals. Marsupialia consists of nearly 350 extant species divided into 4 Australasian and 3 South American orders [Nilsson et al, 2010;Gallus et al, 2015;May-Collado et al, 2015]. While the neuroanatomy, connectivity, neocortical development, and physiology of the brain in some representative marsupial species have been studied [Saunders et al, 1989;Rosa et al, 1999;Ashwell et al, 2008;Wong and Kaas, 2009;Watson et al, 2012], little is known about the cellular composition of marsupial brains and how it compares with other clades, besides a report of a low neuronal density in the neocortex of a single species, the opossum (Didelphis virginiana) , in comparison to other mammals [Haug, 1987].…”

Section: Introductionmentioning

confidence: 99%

Cellular Scaling Rules for the Brains of Marsupials: Not as “Primitive” as Expected

Santos

Porfírio²,

Cunha³

et al. 2017

Brain Behav Evol

1,837

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In the effort to understand the evolution of mammalian brains, we have found that common relationships between brain structure mass and numbers of nonneuronal (glial and vascular) cells apply across eutherian mammals, but brain structure mass scales differently with numbers of neurons across structures and across primate and nonprimate clades. This suggests that the ancestral scaling rules for mammalian brains are those shared by extant nonprimate eutherians - but do these scaling relationships apply to marsupials, a sister group to eutherians that diverged early in mammalian evolution? Here we examine the cellular composition of the brains of 10 species of marsupials. We show that brain structure mass scales with numbers of nonneuronal cells, and numbers of cerebellar neurons scale with numbers of cerebral cortical neurons, comparable to what we have found in eutherians. These shared scaling relationships are therefore indicative of mechanisms that have been conserved since the first therians. In contrast, while marsupials share with nonprimate eutherians the scaling of cerebral cortex mass with number of neurons, their cerebella have more neurons than nonprimate eutherian cerebella of a similar mass, and their rest of brain has fewer neurons than eutherian structures of a similar mass. Moreover, Australasian marsupials exhibit ratios of neurons in the cerebral cortex and cerebellum over the rest of the brain, comparable to artiodactyls and primates. Our results suggest that Australasian marsupials have diverged from the ancestral Theria neuronal scaling rules, and support the suggestion that the scaling of average neuronal cell size with increasing numbers of neurons varies in evolution independently of the allocation of neurons across structures.

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“…We adopted composite phylogenetic trees for our study taxa (Archibald, 1998; Beck, 2012; Bi et al, 2014; Cardillo et al, 2004; Forasiepi et al, 2006; Gatesy et al, 2013; Goloboff et al, 2009; Kielan-Jaworowska, Cifelli & Luo, 2004; Luo, Kielan-Jaworowska & Cifelli, 2002; Luo et al, 2003; Luo, 2007a, 2007b; May-Collado, Kilpatrick & Agnarsson, 2015; Meredith et al, 2009; Meredith et al, 2011; Mitchell et al, 2014; O’Leary et al, 2013; O’Leary & Gatesy, 2008; dos Reis et al, 2012; Rose, 2006; Sánchez-Villagra et al, 2007; Song et al, 2012; Spaulding, O’Leary & Gatesy, 2009; Springer et al, 2003, 2007; Springer, Krajewski & Meredith, 2009; Thewissen, 1990; Thewissen et al, 2007; Wible et al, 2007; Zack et al, 2005). As defined by several authors, the clade Mammaliaformes includes crown group Mammalia plus closely related extinct stem-mammals such as the iconic Morganucodon and the more recently discovered Sinoconodon , and is characterized by diagnostic features involving the teeth, jaw and inner ear (Kielan-Jaworowska, Cifelli & Luo, 2004; Rose, 2006).…”

Section: Methodsmentioning

confidence: 99%

Evolution of the patellar sesamoid bone in mammals

Samuels

Regnault

Hutchinson

2017

PeerJ

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The patella is a sesamoid bone located in the major extensor tendon of the knee joint, in the hindlimb of many tetrapods. Although numerous aspects of knee morphology are ancient and conserved among most tetrapods, the evolutionary occurrence of an ossified patella is highly variable. Among extant (crown clade) groups it is found in most birds, most lizards, the monotreme mammals and almost all placental mammals, but it is absent in most marsupial mammals as well as many reptiles. Here, we integrate data from the literature and first-hand studies of fossil and recent skeletal remains to reconstruct the evolution of the mammalian patella. We infer that bony patellae most likely evolved between four and six times in crown group Mammalia: in monotremes, in the extinct multituberculates, in one or more stem-mammal genera outside of therian or eutherian mammals and up to three times in therian mammals. Furthermore, an ossified patella was lost several times in mammals, not including those with absent hindlimbs: once or more in marsupials (with some re-acquisition) and at least once in bats. Our inferences about patellar evolution in mammals are reciprocally informed by the existence of several human genetic conditions in which the patella is either absent or severely reduced. Clearly, development of the patella is under close genomic control, although its responsiveness to its mechanical environment is also important (and perhaps variable among taxa). Where a bony patella is present it plays an important role in hindlimb function, especially in resisting gravity by providing an enhanced lever system for the knee joint. Yet the evolutionary origins, persistence and modifications of a patella in diverse groups with widely varying habits and habitats—from digging to running to aquatic, small or large body sizes, bipeds or quadrupeds—remain complex and perplexing, impeding a conclusive synthesis of form, function, development and genetics across mammalian evolution. This meta-analysis takes an initial step toward such a synthesis by collating available data and elucidating areas of promising future inquiry.

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Mammals from ‘down under’: a multi-gene species-level phylogeny of marsupial mammals (Mammalia, Metatheria)

Cited by 62 publications

References 87 publications

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

Cellular Scaling Rules for the Brains of Marsupials: Not as “Primitive” as Expected

Evolution of the patellar sesamoid bone in mammals

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