Jurassic stem-mammal perinates and the origin of mammalian reproduction and growth

@article{Hoffman2018JurassicSP,
  title={Jurassic stem-mammal perinates and the origin of mammalian reproduction and growth},
  author={Eva A. Hoffman and Timothy Rowe},
  journal={Nature},
  year={2018},
  volume={561},
  pages={104-108}
}
Transformations in morphology, physiology and behaviour along the mammalian stem lineage were accompanied by profound modifications to reproduction and growth, including the emergence of a reproductive strategy characterized by high maternal investment in a small number of offspring1,2 and heterochronic changes in early cranial development associated with the enlargement of the brain3. Because direct fossil evidence of these transitions is lacking, the timing and sequence of these modifications… 
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TLDR
It is reported, using synchrotron X-ray tomographic imaging of incremental tooth cementum, that Morganucodon and Kuehneotherium had maximum lifespans considerably longer than comparably sized living mammals, but similar to those of reptiles, and so they likely had reptilian-level basal metabolic rates.
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The earliest-known mandibular fossil of a mammaliaform with double molariform roots and a crown with two rows of cusps from the Late Triassic of Greenland is described and indicates that teeth with two roots can better withstand stronger mechanical stresses like those resulting from tooth occlusion, than teeth with a single root.
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TLDR
Synchrotron X-ray imaging of incremental tooth cementum shows two Early Jurassic stem-mammals, Morganucodon and Kuehneotherium, had lifespans considerably longer than comparably sized living mammals, but similar to reptile-like physiology, and maximum metabolic rates increased evolutionarily before basal rates.
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TLDR
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TLDR
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TLDR
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TLDR
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References

SHOWING 1-10 OF 36 REFERENCES
Developmental palaeontology in synapsids: the fossil record of ontogeny in mammals and their closest relatives
  • M. Sánchez-Villagra
  • Environmental Science, Geography
    Proceedings of the Royal Society B: Biological Sciences
  • 2010
TLDR
Developmental palaeontology is relevant for the discourse of ecological developmental biology, an area of research where features of growth and variation are fundamental and accessible among fossil mammals.
Reproduction in Early Amniotes
TLDR
Exceptional insights into early amniote reproduction are offered by recent fossil discoveries, and the fact that these fossils come from ancient seas and lakes and not from dry land helps to explain the paradox that there is an older fossil record for live-bearing amniotes than for egg laying in ammiotes.
Heterochrony in limb evolution: developmental mechanisms and natural selection.
The tetrapod limb provides several examples of heterochrony-changes in the timing of developmental events. These include species differences in the sequence of skeletal chondrogenesis, in gene
Mammalian skull heterochrony reveals modular evolution and a link between cranial development and brain size
TLDR
It is argued that cranial heterochrony in mammals has occurred in concert with encephalization but within a conserved modular organization.
Mandibular and dental characteristics of Late Triassic mammaliaform Haramiyavia and their ramifications for basal mammal evolution
TLDR
Tests of competing phylogenetic hypotheses with new data show that Late Triassic haramiyids are a separate clade from multituberculate mammals and are excluded from the Mammalia, suggesting that dietary diversification is a major factor in the earliest mammaliaform evolution.
Ontogeny of the Early Triassic Cynodont Thrinaxodon liorhinus (Therapsida): Cranial Morphology
TLDR
The large number of changes in the temporal region of the skull of Thrinaxodon may indicate a greater development of the posterior fibres of the temporalis musculature from an early ontogenetic stage, indicating a strong posterodorsal movement of the mandible in Thrinrix.
MONOTREME OSSIFICATION SEQUENCES AND THE RIDDLE OF MAMMALIAN SKELETAL DEVELOPMENT
  • V. Weisbecker
  • Biology
    Evolution; international journal of organic evolution
  • 2011
TLDR
The first postcranial ossification sequences of the monotreme echidna and platypus are presented, and these are compared with published data from other mammals and amniotes to suggest marsupials may not represent the ancestral mammalian condition.
On the Evolution and Adaptive Significance of Postnatal Growth Rates in the Terrestrial Vertebrates
  • T. Case
  • Biology, Environmental Science
    The Quarterly Review of Biology
  • 1978
TLDR
The results of this analysis support the notion that growth rate is adapted to certain features of an animal's environment, which will be altered in an empirically appropriate direction with changes in these environmental parameters.
Definition, diagnosis, and origin of Mammalia
TLDR
Triassic and Early Jurassic taxa commonly referred to as mammals, including Morganucodontidae, Kuehneotheriidae, and Haramiyidae, were found to lie outside of Mammalia.
...
1
2
3
4
...