author={Zhe‐Xi Luo and Zofia Kielan-Jaworowska and Richard. Cifelli},
Abstract We provide a review of dental replacement features in stem clades of mammals and an hypothetical outline for the evolution of replacement frequency, mode, and sequence in early mammalian evolution. The origin of mammals is characterized by a shift from a primitive pattern of multiple, alternating replacements of all postcanines in most cynodonts to a derived pattern of single, sequential replacement of postcanines. The stem mammal Sinoconodon, however, retained some primitive… 

Enamel formation and growth in non-mammalian cynodonts

It is possible that the reduction in enamel extension rates in mammaliamorphs reflects an underlying reduction in skeletal growth rates at the time of postcanine formation, due to a more abruptly terminating pattern of adult growth in these more mammal-like, crownward species.

Diphyodont tooth replacement of Brasilodon—A Late Triassic eucynodont that challenges the time of origin of mammals

Two sets of teeth (diphyodonty) characterise extant mammals but not reptiles, as they generate many replacement sets (polyphyodonty). The transition in long‐extinct species from many sets to only two

The evolution of the synapsid tusk: insights from dicynodont therapsid tusk histology

The evolution of an ever-growing dentition, such as a tusk, is predicated on the evolution of significantly reduced tooth replacement and a permanent soft-tissue attachment, which helps to explain why tusks are restricted to this clade among extant vertebrates.

Developmental origins and homologies of the hyracoid dentition

The results point out the labile position of vestigial upper teeth on jaw bones in extant species, associated with the frequently unusual premolar shape of deciduous canines over 50 Ma of hyracoid evolution.

Heterochrony, dental ontogenetic diversity, and the circumvention of constraints in marsupial mammals and extinct relatives

Analysis of the sequence of eruption of 76 specimens of metatherians, including Sparassodonta, an extinct clade of specialized carnivores from South America, shows specialization in the timing of dental eruption and in the deciduous tooth shape of sparASSodonts are evolutionary mechanisms that circumvent constraints imposed by the metatherian replacement pattern and increase morphological disparity during ontogeny.

Dental Eruption Series and Replacement Pattern in Miocene Prosantorhinus (Rhinocerotidae) as Revealed by Macroscopy and X-ray: Implications for Ontogeny and Mortality Profile

An exceptionally high number of juvenile dentaries at different developmental stages including highly fragile tooth germs of the extinct rhinoceros Prosantorhinus germanicus from the Miocene fossil lagerstätte Sandelzhausen in Germany are analyzed, indicating a gradual accumulation of corpses (attritional fossil assemblage).

The evolution of growth patterns in mammalian versus nonmammalian cynodonts

Investigation of growth patterns in the tritylodontid cynodont Oligokyphus and the basal mammaliaform Morganucodon provides insight into this crucial transition into mammalia form, suggesting a gradual evolution of mammalian growth patterns across the Cynodont to mammalia Form transition.

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
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.

Unexpected evolutionary patterns of dental ontogenetic traits in cetartiodactyl mammals

This study mainly shows that eruption sequences reliably characterize higher level cetartiodactyl taxa and could represent a new source of phylogenetic characters, especially to disentangle the origin of hippopotamoids and cetaceans.

Early evidence of molariform hypsodonty in a Triassic stem-mammal

New fossils of the stem-mammal Menadon besairiei from the Late Triassic are described, which show the convergent evolution of hypsodonty before mammals and highlight the constraints imposed by limited tooth replacement and tooth wear in the evolutionary trajectories of herbivorous mammals and stem-Mammals.




From the poyphyodont replacement and the substantial growth of the adultskulls of Anoconodon, it is inferred that this taxon lacked the lactation and determinategrowth typical of living mammals.

Origin of the tooth-replacement pattern in therian mammals: evidence from a 110 Myr old fossil

Slaughteria provides the first direct evidence of a tooth–replacement pattern that is plausible for the common ancestor of all therians, and has only one adult molar in place and contains two mental foramina in the jaw.

Patterns of tooth eruption and replacement in multituberculate mammals

ABSTRACT Dentitions of juvenile multituberculate mammals are rarely preserved in the fossil record. A previously undescribed skull and jaws of a juvenile individual of Taeniolabis taoensis contains

Fossil evidence for the origin of the marsupial pattern of tooth replacement

An ultra-high-resolution X-ray computed tomography study of the tiny fossil Alphadon is presented, which represents the first evidence of dental development and replacement in a Mesozoic marsupial.

Ontogenetic Evidence for Dental Homologies and Premolar Replacement in Fossil and Extant Caenolestids (Marsupialia)

It is suggested that examination of other specimens of juvenile dentitions, skulls, and skeletons in museum collections can provide additional insight into the developmental and evolutionary biology of mammals.

In quest for a phylogeny of Mesozoic mammals

A phylogeny of all major groups of Mesozoic mammals based on phylogenetic analyses of 46 taxa and 275 osteological and dental characters, using parsimony methods is proposed, suggesting that the “obtuse−angle symmetrodonts” are paraphyletic, and that they lack reliable and unambiguous synapomorphies.

A Theory of the Evolution of Therian Dental Formulas and Replacement Patterns

  • A. Ziegler
  • Medicine
    The Quarterly Review of Biology
  • 1971
Generally, molar number decreased from eight or nine in the ancestral therapsid and primitive pantothere to four in the mid-Cretaceous eupantotherian stock, and antemolar number has seldom, and perhaps never, increased.

Sequence of emergence of the permanent teeth in Macaca, Pan, Homo, and Australopithecus: Its evolutionary significance

  • B. Smith
  • Biology
    American journal of human biology : the official journal of the Human Biology Council
  • 1994
The human condition is considered by comparing us to other living primates and to the authors' evolutionary past and considered in the light of Schultz's hypothesis that sequence of tooth emergence is adapted to rate of postnatal growth.

First Evidence of Tooth Replacement in the Subclass Allotheria ( Mammalia ) BY

Multituberculates (the only known order of the subclass Allotheria) are abundantly represented in Mesozoic and Paleocene mammal localities. Of the relatively large number of multituberculate

The primitive eutherian dental formula

Various lines of paleontological evidence support the theory, first emphasized by McKenna (1975), that eutherians primitively had at least five premolars, with the most likely transformation to the four premolar number involved the loss of a premolar in the middle of the series.