Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont

  title={Transitional mammalian middle ear from a new Cretaceous Jehol eutriconodont},
  author={Jin Meng and Yuanqing Wang and Chuankui Li},
The transference of post-dentary jaw elements to the cranium of mammals as auditory ossicles is one of the central topics in evolutionary biology of vertebrates. Homologies of these bones among jawed vertebrates have long been demonstrated by developmental studies; but fossils illuminating this critical transference are sparse and often ambiguous. Here we report the first unambiguous ectotympanic (angular), malleus (articular and prearticular) and incus (quadrate) of an Early Cretaceous… 
Exploring ancestral phenotypes and evolutionary development of the mammalian middle ear based on Early Cretaceous Jehol mammals
The evolutionary changes recorded in the Mesozoic mammals are largely consistent with the middle ear morphogenesis during the ontogeny of extant mammals, supporting the relation between evolution and development.
Cretaceous fossil reveals a new pattern in mammalian middle ear evolution
The findings suggest that the co-evolution of the primary and secondary jaw joints in allotherians was an evolutionary adaptation allowing feeding with unique palinal (longitudinal and backwards) chewing, and the evolution of the allotherian auditory apparatus was probably triggered by the functional requirements of the feeding apparatus.
Ear ossicle morphology of the Jurassic euharamiyidan Arboroharamiya and evolution of mammalian middle ear
The stapes and incus of the euharamiyidan Arboroharamiya from the lower Upper Jurassic of northern China are reported, which represent the earliest known mammalian middle ear ossicles and suggest development of the definitive mammalianmiddle ear (DMME), which has evolved at least three times independently in mammals.
Evolution of the Middle and Inner Ears of Mammaliaforms: The Approach to Mammals
The homoplasies of ear structures in early mammalian evolution, although seemingly complex, are consistent with the new understanding of a labile morphogenesis of mammalian ears under a complex developmental genetic network.
Disconnecting bones within the jaw‐otic network modules underlies mammalian middle ear evolution
The analysis allows the identification of three types of anatomical modules evolving through five evolutionary stages during the anatomical transformation of the jawbones into middle ear bones, with the ossification and degradation of Meckel's cartilage in mammals as the key ontogenetic event leading the change of anatomical modularity.
The earliest known mammalian stapes with unequivocal morphology from an Early Cretaceous eutriconodontan, Chaoyangodens lii, is described. The stapes is roughly rectangular in dorsal view with
Mammalian evolution: A jaw-dropping ear
A fossil from the Early Cretaceous provides insight into the evolution of the hearing apparatus in mammals and shows that Meckel's cartilage was a vital piece in the evolutionary jigsaw that led to the formation of the mammalian middle ear.
Mammalian development does not recapitulate suspected key transformations in the evolutionary detachment of the mammalian middle ear
It is shown that neither allometric nor topological change is quantifiable in the pre-detachment ME development of six marsupials and two monotremes, and this challenges the developmental prerequisites of widely cited evolutionary scenarios of definitive mammalian middle ear (DMME) evolution.
A monotreme-like auditory apparatus in a Middle Jurassic haramiyidan.
It is proposed that the overlapping incudomallear articulation found in this and other Mesozoic fossils, in extant monotremes and in early ontogeny in extant marsupials and placentals is a morphology that evolved in several groups of mammals in the transition from the dual to the single function for the ossicles.
The Evolution and Development of Middle Ears in Land Vertebrates
New fossil evidence and supporting data from embryological studies have helped to consolidate interpretations of the structures that assemble the middle ear apparatus of different lineages of land


Evolutionary Development of the Middle Ear in Mesozoic Therian Mammals
A Cretaceous trechnotherian mammal with an ossified Meckel’s cartilage in the adult is reported, showing that homoplastic evolution of the DMME occurred in derived therian mammals, besides the known cases of eutriconodonts.
Phylogeny and Ontogeny of Mammalian Middle Ear Structures
Fossil finds of advanced cynodonts and early mammals demonstrate that within the synapsids a new sound transforming system evolved at the posterior angle of the mandible, which is most probably not homologous to that of sauropsids.
A new eutriconodont mammal and evolutionary development in early mammals
A Mesozoic eutriconodont nested within crown mammals that clearly illustrates this transition: the middle ear bones are connected to the mandible via an ossified Meckel’s cartilage, adding to the evidence of homoplasy of vertebral characters in the thoraco-lumbar transition and unfused lumbar ribs among early mammals.
The ossified Meckel's cartilage and internal groove in Mesozoic mammaliaforms: implications to origin of the definitive mammalian middle ear
These specimens provide direct evidence for the function of the internal groove which is commonly present in the dentary of early mammals and their relatives and supports the assumption that a persistent or ossified Meckel's cartilage has been present in adults of the common ancestor of mammals.
Monotreme affinities and low-frequency hearing suggested by multituberculate ear
The discovery of a multituberculate ectotympanic bone, associated with the malleus in original life position, from two exquisitely preserved auditory regions, documents incorporation of the angular and prearticular bones into the middle ear of multituberculated mammals, favouring the hypothesized single origin of the ossicular chain in mammals.
Ontogenetic and phylogenetic transformations of the ear ossicles in marsupial mammals
This study is based on the examination of histological sections of specimens of different ages and of adult ossicles from macerated skulls representing a wide range of taxa and aims at addressing
History of studies on mammalian middle ear evolution: a comparative morphological and developmental biology perspective.
  • M. TakechiS. Kuratani
  • Biology, Geography
    Journal of experimental zoology. Part B, Molecular and developmental evolution
  • 2010
It is proposed that to understand mammalian middle ear evolution, it is essential to identify the critical developmental events underlying the particular mammalian anatomy and to describe the evolutionary sequence of changes in developmental and molecular terms.
Middle-ear ossicles of the multituberculate Kryptobaatar from the Mongolian late Cretaceous : implications for mammaliamorph relationships and the evolution of the auditory apparatus. American Museum novitates ; no. 3187
Partial malleus, ectotympanic, and stylohyal along with a fragment of a possible stapes are described for the multituberculate Kryptobaatar dashzevegi from the Late Cretaceous of Mongolia. The
The skull of Morganucodon
Two species of triconodont (atherian) mammal from the Lower Jurassic are described: M. oehleri from China and M. watsoni from Wales; the systematic position of Morganucodon is discussed.
Evolution of the Auditory System in Synapsida (“Mammal-Like Reptiles” and Primitive Mammals) as Seen in the Fossil Record
The present chapter examines the extensive fossil evidence concerning the nature of the auditory machinery of early mammals and their antecedents.