Summary of Laurasiatheria (Mammalia) Phylogeny

Hu, Jingyang; Zhang, Yaping; Yu, Li

doi:10.3724/sp.j.1141.2012.e05-06e65

Cited by 13 publications

(11 citation statements)

References 95 publications

(131 reference statements)

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“…Each lineage crossing the K-Pg boundary evolved and speciated rapidly, with eutherians, like metatherians, quickly exploring ecomorphospace [57,65]. Scrotifera diversified particularly quickly, resulting in the complex patterns of relationships associated with incomplete lineage sorting within the clade [25,66]. This scenario is identical in many respects to the 'soft explosive' model of Phillips [15] except for the timing of the divergence of Xenarthra and Afrotheria.…”

Section: Discussionmentioning

confidence: 91%

Rapid morphological evolution in placental mammals post-dates the origin of the crown group

et al. 2019

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Resolving the timing and pattern of early placental mammal evolution has been confounded by conflict among divergence date estimates from interpretation of the fossil record and from molecular-clock dating studies. Despite both fossil occurrences and molecular sequences favouring a Cretaceous origin for Placentalia, no unambiguous Cretaceous placental mammal has been discovered. Investigating the differing patterns of evolution in morphological and molecular data reveals a possible explanation for this conflict. Here, we quantified the relationship between morphological and molecular rates of evolution. We show that, independent of divergence dates, morphological rates of evolution were slow relative to molecular evolution during the initial divergence of Placentalia, but substantially increased during the origination of the extant orders. The rapid radiation of placentals into a highly morphologically disparate Cenozoic fauna is thus not associated with the origin of Placentalia, but post-dates superordinal origins. These findings predict that early members of major placental groups may not be easily distinguishable from one another or from stem eutherians on the basis of skeleto-dental morphology. This result supports a Late Cretaceous origin of crown placentals with an ordinal-level adaptive radiation in the early Paleocene, with the high relative rate permitting rapid anatomical change without requiring unreasonably fast molecular evolutionary rates. The lack of definitive Cretaceous placental mammals may be a result of morphological similarity among stem and early crown eutherians, providing an avenue for reconciling the fossil record with molecular divergence estimates for Placentalia.

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Section: Discussionmentioning

confidence: 91%

Rapid morphological evolution in placental mammals post-dates the origin of the crown group

et al. 2019

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“…As a result, Primates, Dermoptera, and Scandentia, all certainly monophyletic, were allowed to vary in their interrelationships within Euarchonta. Within Laurasiatheria, there is no clear consensus for the relationships of the orders (Hallstrom et al , ; Hu et al , ), except that Carnivora and Pholidota are likely to be sister taxa (Nishihara et al , ; Zhou et al , ). Raoellid artiodactyls (including Indohyus ) are considered to be closer relatives of cetaceans than other artiodactyls in this analysis (Bajpai, Thewissen & Sahni, ), and as a result, the topologies within Artiodactyla were also constrained to reflect this basal division.…”

Section: Methodsmentioning

confidence: 99%

“…In applying molecular constraints, we allowed for areas of uncertainty such as the topology of the Laurasiatherian orders (Hu, Zhang & Yu, 2012) and the relationships between Boreoeutheria, Atlantogenata and Xenarthra (Murphy et al, 2007;Nishihara, Maruyama & Okada, 2009), discussed further below, by treating them as unresolved polytomies within the scaffold. Two levels of constraint were implemented; one imposed a 'minimum' constraint, including a limited subset of exemplar taxa as representatives of the extant orders.…”

Section: (B) Constraints On Tree Topologymentioning

confidence: 99%

Resolving the relationships of Paleocene placental mammals

2015

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The 'Age of Mammals' began in the Paleocene epoch, the 10 million year interval immediately following the Cretaceous-Palaeogene mass extinction. The apparently rapid shift in mammalian ecomorphs from small, largely insectivorous forms to many small-to-large-bodied, diverse taxa has driven a hypothesis that the end-Cretaceous heralded an adaptive radiation in placental mammal evolution. However, the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters. We improve the resolution of the relationships of several enigmatic Paleocene clades, including families of 'condylarths'. Protungulatum is resolved as a stem eutherian, meaning that no crown-placental mammal unambiguously pre-dates the Cretaceous-Palaeogene boundary. Our results support an Atlantogenata-Boreoeutheria split at the root of crown Placentalia, the presence of phenacodontids as closest relatives of Perissodactyla, the validity of Euungulata, and the placement of Arctocyonidae close to Carnivora. Periptychidae and Pantodonta are resolved as sister taxa, Leptictida and Cimolestidae are found to be stem eutherians, and Hyopsodontidae is highly polyphyletic. The inclusion of Paleocene taxa in a placental phylogeny alters interpretations of relationships and key events in mammalian evolutionary history. Paleocene mammals are an essential source of data for understanding fully the biotic dynamics associated with the end-Cretaceous mass extinction. The relationships presented here mark a critical first step towards accurate reconstruction of this important interval in the evolution of the modern fauna.

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“…True laurasiatherian taxa are known from the fossil record from the early Eocene on, but likewise to the other supraordinal clade an origin that harks back to Paleocene or Cretaceous times seems to be likely [83,84,112]. Then, a very rapid evolutionary radiation was assumed [132]. Laurasiatheria contain Cetartiodactyla (even-toed ungulates or hoofed mammals, known as Artiodactyla, with camels, pigs, ruminants (giraffes, deer, antelopes, cattle, sheep, goats), and hippopotamus as well as whales and dolphins, formerly known as Cetacea) and Perissodactlya (odd-toed ungulates, such as horses, tapirs, and rhinoceroses).…”

Section: Laurasiatheriamentioning

confidence: 99%

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

Mess

2014

Advances in Biology

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Here a survey of placental evolution is conducted. Placentation is a key factor for the evolution of placental mammals that had evolved an astonishing diversity. As a temporary organ that does not allow easy access, it is still not well understood. The lack of data also is a restriction for better understanding of placental development, structure, and function in the human. Animal models are essential, because experimental access to the human placenta is naturally restricted. However, there is not a single ideal model that is entirely similar to humans. It is particularly important to establish other models than the mouse, which is characterised by a short gestation period and poorly developed neonates that may provide insights only for early human pregnancy. In conclusion, current evolutionary studies have contributed essentially to providing a pool of experimental models for recent and future approaches that may also meet the requirements of a long gestation period and advanced developmental status of the newborn in the human. Suitability and limitations of taxa as alternative animal models are discussed. However, further investigations especially in wildlife taxa should be conducted in order to learn more about the full evolutionary plasticity of the placenta system.

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Summary of Laurasiatheria (Mammalia) Phylogeny

Cited by 13 publications

References 95 publications

Rapid morphological evolution in placental mammals post-dates the origin of the crown group

Rapid morphological evolution in placental mammals post-dates the origin of the crown group

Resolving the relationships of Paleocene placental mammals

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

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