Mesozoic Mammals and the Polyphyletic Origin of Mammals

Evolution ◽  
1959 ◽  
Vol 13 (3) ◽  
pp. 405 ◽  
Author(s):  
George Gaylord Simpson
Keyword(s):  
Mesozoic Mammals

Mesozoic Mammals from South America and Their Forerunners

2021 ◽  
Author(s):  
Guillermo W. Rougier ◽  
Agustín G. Martinelli ◽  
Analía M. Forasiepi
Keyword(s):  
South America ◽  
Mesozoic Mammals

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.

Mesozoic mammals and early mammalian brain diversity

2003 ◽  
Vol 26 (5) ◽  
pp. 556-557 ◽  
Author(s):  
Emmanuel Gilissen ◽  
Thierry Smith
Keyword(s):  
Middle Ear ◽  
Brain Regions ◽  
Mammalian Brain ◽  
Fossil Remains ◽  
Ear Ossicles ◽  
Mesozoic Mammals ◽  
Brain Expansion ◽  
The Relationship ◽  
The Brain

Fossil remains witness the relationship between the appearance of the middle ear and the expansion of the brain in early mammals. Nevertheless, the lack of detachment of ear ossicles in the mammaliaform Morganucodon, despite brain enlargement, points to other factors that triggered brain expansion in early mammals. Moreover, brain expansion in some early mammalian groups seems to have favored brain regions other than the cortex.

Molar Evolution in Mesozoic Mammals

1967 ◽  
Vol 46 (5) ◽  
pp. 792-795 ◽  
Author(s):  
K.A. Kermack
Keyword(s):  
Mesozoic Mammals

Mesozoic Mammals: Mammalian Dark Ages

Nature ◽  
1970 ◽  
Vol 227 (5253) ◽  
pp. 17-18
Author(s):  
Keyword(s):  
Dark Ages ◽  
Mesozoic Mammals

Large Mesozoic mammals fed on young dinosaurs

Nature ◽  
2005 ◽  
Vol 433 (7022) ◽  
pp. 149-152 ◽  
Author(s):  
Yaoming Hu ◽  
Jin Meng ◽  
Yuanqing Wang ◽  
Chuankui Li
Keyword(s):  
Mesozoic Mammals

First record of Mesozoic mammals from Saskatchewan

1980 ◽  
Vol 17 (4) ◽  
pp. 512-519 ◽  
Author(s):  
Paul A. Johnston
Keyword(s):  
First Record ◽  
Hell Creek Formation ◽  
Mesozoic Mammals

The discovery of mammalian fossils in the sandy phase of the Frenchman Formation of Saskatchewan documents the first record of Mesozoic mammals from that province, and from Canada outside of Alberta. Mammals identified include Mesodma (Multituberculata), a didelphid marsupial, a species of Cimolestes (Insectivora) apparently structurally intermediate between C. cerberoides and Procerberus formicarum, and Protungulatum (Condylarthra). Elsewhere in Cretaceous strata, Protungulatum occurs only in the Hell Creek beds of Montana, thereby corroborating the hypothesis that the Frenchman and Hell Creek formations are chronostrati-graphically equivalent. The presence of Protungulatum and the dominance of placentals rather than marsupials in the sample document a facies of apparent Paleocene aspect, resembling that at certain sites in the Hell Creek Formation of Montana, and otherwise unknown in the Cretaceous.

Sign in / Sign up

Export Citation Format

Share Document