scholarly journals Global determinants and conservation of evolutionary and geographic rarity in land vertebrates

2021 ◽  
Vol 7 (42) ◽  
Author(s):  
Gopal Murali ◽  
Rikki Gumbs ◽  
Shai Meiri ◽  
Uri Roll
Keyword(s):  
Land Vertebrates

scholarly journals Large‐scale evolution of body temperatures in land vertebrates

2021 ◽  
Author(s):  
Matthew O. Moreira ◽  
Yan‐Fu Qu ◽  
John J. Wiens
Keyword(s):  
Large Scale ◽  
Body Temperatures ◽  
Land Vertebrates ◽  
Scale Evolution

Pax6 expression highlights regional organization in the adult brain of lungfishes, the closest living relatives of land vertebrates

2019 ◽  
Vol 528 (1) ◽  
pp. 139-163
Author(s):  
Jesús M. López ◽  
Ruth Morona ◽  
Nerea Moreno ◽  
Daniel Lozano ◽  
Sara Jiménez ◽  
...  
Keyword(s):  
Adult Brain ◽  
Pax6 Expression ◽  
Regional Organization ◽  
Land Vertebrates

The Terrestrial Environment and the Origin of Land Vertebrates

Evolution ◽  
1981 ◽  
Vol 35 (5) ◽  
pp. 1027
Author(s):  
Everett C. Olson ◽  
A. L. Panchen
Keyword(s):  
Terrestrial Environment ◽  
Land Vertebrates

scholarly journals Mammalian development does not recapitulate suspected key transformations in the evolution of the mammalian middle ear

2015 ◽  
Author(s):  
Héctor Ramirez-Chaves ◽  
Stephen Wroe ◽  
Lynne Selwood ◽  
Lyn Hinds ◽  
Chris Leigh ◽  
...  
Keyword(s):  
Middle Ear ◽  
Mammalian Development ◽  
Positional Change ◽  
Lower Jaw ◽  
Dental Eruption ◽  
Mesozoic Mammals ◽  
Differential Positioning ◽  
Jaw Joint ◽  
Early Mammalian Development ◽  
Land Vertebrates

The tympanic ring, malleus and incus of the mammalian middle ear (MME) derive from the ancestral primary jaw joint of land vertebrates. In Mesozoic mammals, evolutionary detachment of the MME from the lower jaw occurred when Meckel’s cartilage - the last connection between MME and dentary – disappeared. This disappearance is famously recapitulated in early mammalian development. Further developmental recapitulation of Mesozoic MME detachment is thought to occur in the form of negative allometry and posterior/medial replacement of MME bones relative to the jaw joint. However, despite being widely accepted, such detailed recapitulation scenarios have never been quantified. Here we show, based on µCT scans of developmental series of several marsupials and monotremes, that negative allometry of MME bones relative to the skull occurs only after MME detachment, ruling it out as a developmental detachment trigger; additionally, there is no positional change of ectotympanic or malleus relative to the dentary. Differential positioning of MME bones in the two monotreme species is also not developmentally recapitulated. Our results challenge the developmental prerequisites of widely accepted evolutionary scenarios regarding MME detachment. Rather, we observe an association of MME detachment and dental eruption, suggesting a detachment trigger relating to the onset of dentary function.

In search of possible causes of mass extinctions

2004 ◽  
Author(s):  
Tony Hallam
Keyword(s):  
Science Fiction ◽  
High Rate ◽  
Mass Extinctions ◽  
Geological Time ◽  
Steven Spielberg ◽  
Geological Past ◽  
History Of ◽  
The Subject ◽  
Cretaceous Period ◽  
Land Vertebrates

When the subject of extinctions in the geological past comes up, nearly everyone’s thoughts turn to dinosaurs. It may well be true that these long-extinct beasts mean more to most children than the vast majority of living creatures. One could even go so far as to paraphrase Voltaire and maintain that if dinosaurs had never existed it would have been necessary to invent them, if only as a metaphor for obsolescence. To refer to a particular machine as a dinosaur would certainly do nothing for its market value. The irony is that the metaphor is now itself obsolete. The modern scientific view of dinosaurs differs immensely from the old one of lumbering, inefficient creatures tottering to their final decline. Their success as dominant land vertebrates through 165 million years of the Earth’s history is, indeed, now mainly regarded with wonder and even admiration. If, as is generally thought, the dinosaurs were killed off by an asteroid at the end of the Cretaceous, that is something for which no organism could possibly have been prepared by normal Darwinian natural selection. The final demise of the dinosaurs would then have been the result, not of bad genes, but of bad luck, to use the laconic words of Dave Raup. In contemplating the history of the dinosaurs it is necessary to rectify one widespread misconception. Outside scientific circles the view is widely held that the dinosaurs lived for a huge slice of geological time little disturbed by their environment until the final apocalypse. This is a serious misconception. The dinosaurs suffered quite a high evolutionary turnover rate, and this implies a high rate of extinction throughout their history. Jurassic dinosaurs, dominated by giant sauropods, stegosaurs, and the top carnivore Allosaurus, are quite different from those of the Cretaceous period, which are characterized by diverse hadrosaurs, ceratopsians, and Tyrannosaurus. Michael Crichton’s science-fiction novel Jurassic Park, made famous by the Steven Spielberg movies, features dinosaurs that are mainly from the Cretaceous, probably because velociraptors and Tyrannosaurus could provide more drama.

scholarly journals Mammalian development does not recapitulate suspected key transformations in the evolutionary detachment of the mammalian middle ear

2016 ◽  
Vol 283 (1822) ◽  
pp. 20152606 ◽  
Author(s):  
Héctor E. Ramírez-Chaves ◽  
Stephen W. Wroe ◽  
Lynne Selwood ◽  
Lyn A. Hinds ◽  
Chris Leigh ◽  
...  
Keyword(s):  
Middle Ear ◽  
Functional Divergence ◽  
Mammalian Development ◽  
Meckel's Cartilage ◽  
Topological Change ◽  
Meckel’S Cartilage ◽  
Fossil Evidence ◽  
Jaw Joint ◽  
Land Vertebrates

The ectotympanic, malleus and incus of the developing mammalian middle ear (ME) are initially attached to the dentary via Meckel's cartilage, betraying their origins from the primary jaw joint of land vertebrates. This recapitulation has prompted mostly unquantified suggestions that several suspected—but similarly unquantified—key evolutionary transformations leading to the mammalian ME are recapitulated in development, through negative allometry and posterior/medial displacement of ME bones relative to the jaw joint. Here we show, using µCT reconstructions, that neither allometric nor topological change is quantifiable in the pre-detachment ME development of six marsupials and two monotremes. Also, differential ME positioning in the two monotreme species is not recapitulated. This challenges the developmental prerequisites of widely cited evolutionary scenarios of definitive mammalian middle ear (DMME) evolution, highlighting the requirement for further fossil evidence to test these hypotheses. Possible association between rear molar eruption, full ME ossification and ME detachment in marsupials suggests functional divergence between dentary and ME as a trigger for developmental, and possibly also evolutionary, ME detachment. The stable positioning of the dentary and ME supports suggestions that a ‘partial mammalian middle ear’ as found in many mammaliaforms—probably with a cartilaginous Meckel's cartilage—represents the only developmentally plausible evolutionary DMME precursor.

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