Fossil Evidence on Origin of the Mammalian Brain

  title={Fossil Evidence on Origin of the Mammalian Brain},
  author={Timothy B Rowe and Thomas E. Macrini and Zhe‐Xi Luo},
  pages={955 - 957}
Many hypotheses have been postulated regarding the early evolution of the mammalian brain. [] Key Result We found that relative brain size expanded to mammalian levels, with enlarged olfactory bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two evolutionary pulses. The initial pulse was probably driven by increased resolution in olfaction and improvements in tactile sensitivity (from body hair) and neuromuscular coordination.

Fossils and the Evolution of the Arthropod Brain

Evolving Large and Complex Brains

X-ray studies of two Early Jurassic fossils offer insight into the evolution of mammalian brains, particularly the cerebral hemispheres and cerebellum, which underwent particularly spectacular development in mammals and birds.

The Origins of the Bird Brain: Multiple Pulses of Cerebral Expansion in Evolution

Birds demonstrate extraordinary cognitive and emotional capabilities. The majority of these performances are most likely supported by their developed cerebrum. Birds, as well as mammals, have a much

Brawn before brains in placental mammals after the end-Cretaceous extinction

Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration,

The Organization of Neocortex in Early Mammals

  • J. Kaas
  • Biology, Psychology
    Evolutionary Neuroscience
  • 2020

The Evolution of Mammalian Brains from Early Mammals to Present-Day Primates

Overall the six million years of the evolution of modern humans from early bipedal apes, brains evolved from a great ape size of 400 cc to roughly 1400 cc, with neocortex having an estimated 200 cortical areas occupying 80% of the brain.

The Brain and Inner Ear of the Early Paleocene “Condylarth” Carsioptychus coarctatus: Implications for Early Placental Mammal Neurosensory Biology and Behavior

CT is used to describe the brain, inner ear, sinuses, and endocranial nerves and vessels of Carsioptychus coarctatus, a periptychid “condylarth” that was among the first placentals to blossom during the few million years after the extinction, in the Paleocene, fleshes out the biology of a keystone Paleocene “archaic” placental.

The evolution of brains from early mammals to humans.

  • J. Kaas
  • Biology, Psychology
    Wiley interdisciplinary reviews. Cognitive science
  • 2013
The large size and complex organization of the human brain makes it unique among primate brains. In particular, the neocortex constitutes about 80% of the brain, and this cortex is subdivided into a



Evolution of the Brain and Intelligence

The evidence of the actual evolution of the vertebrate brain is analyzed by reviewing morphological data on endocasts and skeletons of several hundred fossil species and comparing these with living

Coevolution of the Mammalian Middle Ear and Neocortex

Phylogenetic analysis with x-ray computed tomography of fossilized and recent crania implicates differential growth of the neocortex in the evolution and development of the mammalian middle ear. In

A New Mammaliaform from the Early Jurassic and Evolution of Mammalian Characteristics

A fossil from the Early Jurassic represents a new lineage of mammaliaforms, the extinct groups more closely related to the living mammals than to nonmammaliaform cynodonts, and shows that several key mammalian evolutionary innovations in the ear region, the temporomandibular joint, and the brain vault evolved incrementally through mammaliaform evolution and long before the differentiation of the living mammal groups.

Fossil evidence on evolution of inner ear cochlea in Jurassic mammals

The cochlear innervation in Dryolestes is the precursory condition in the curve-to-coil transformation of the cochlea in mammalian phylogeny, which provides the timing of the evolution, and where along the phylogeny the morphogenetic genes were co-opted into patterning the coChlear Innervation.

Description of a cranial endocast from a fossil platypus, Obdurodon dicksoni (Monotremata, Ornithorhynchidae), and the relevance of endocranial characters to monotreme monophyly

A digital cranial endocast of the Miocene platypus Obdurodon dicksoni was extracted from high‐resolution X‐ray computed tomography scans and is therefore important for inferring character support for Monotremata, a clade that is not well diagnosed.

The Endocranial Cavity of a Nonmammalian Eucynodont, Chiniquodon theotenicus, and Its Implications for the Origin of the Mammalian Brain

ABSTRACT The braincase and endocranial cavity of a specimen of a nonmammalian eucynodont Chiniquodon is described and illustrated, and a tentative reconstruction of the gross anatomy of the brain

Phylogenetic Systematics and the Early History of Mammals

In a series of computer parsimony analyses, different rates of evolution in the dentition, skull, and postcranium were responsible for different tree topologies that resulted when different, restricted character samples were analyzed.

A new reconstruction of multituberculate endocranial casts and encephalization quotient of Kryptobaatar

An endocast of the Late Cretaceous Kryptobaatar is described, which differs from those of other multituberculates in having unusually long olfactory bulbs and the paraflocculi elongated transversely, rather than ball−shaped.


Observations of previously undescribed endocasts referable to the Oligocene leptictid Leptictis dakotensis yield new and revised information on the brain features of this species. The neocortex is