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A new eutriconodont mammal and evolutionary development in early mammals.
Nature. 2007 Mar 15; 446(7133):288-93.Nat

Abstract

Detachment of the three tiny middle ear bones from the reptilian mandible is an important innovation of modern mammals. Here we describe 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. The connected ear and jaw structure is similar to the embryonic pattern in modern monotremes (egg-laying mammals) and placental mammals, but is a paedomorphic feature retained in the adult, unlike in monotreme and placental adults. This suggests that reversal to (or retention of) this premammalian ancestral condition is correlated with different developmental timing (heterochrony) in eutriconodonts. This new eutriconodont adds to the evidence of homoplasy of vertebral characters in the thoraco-lumbar transition and unfused lumbar ribs among early mammals. This is similar to the effect of homeobox gene patterning of vertebrae in modern mammals, making it plausible to extrapolate the effects of Hox gene patterning to account for homoplastic evolution of vertebral characters in early mammals.

Authors+Show Affiliations

Carnegie Museum of Natural History, Pittsburgh, Pennysylvania 15213, USA. luoz@carnegiemnh.orgNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

17361176

Citation

Luo, Zhe-Xi, et al. "A New Eutriconodont Mammal and Evolutionary Development in Early Mammals." Nature, vol. 446, no. 7133, 2007, pp. 288-93.
Luo ZX, Chen P, Li G, et al. A new eutriconodont mammal and evolutionary development in early mammals. Nature. 2007;446(7133):288-93.
Luo, Z. X., Chen, P., Li, G., & Chen, M. (2007). A new eutriconodont mammal and evolutionary development in early mammals. Nature, 446(7133), 288-93.
Luo ZX, et al. A New Eutriconodont Mammal and Evolutionary Development in Early Mammals. Nature. 2007 Mar 15;446(7133):288-93. PubMed PMID: 17361176.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A new eutriconodont mammal and evolutionary development in early mammals. AU - Luo,Zhe-Xi, AU - Chen,Peiji, AU - Li,Gang, AU - Chen,Meng, PY - 2006/08/04/received PY - 2007/01/29/accepted PY - 2007/3/16/pubmed PY - 2007/4/12/medline PY - 2007/3/16/entrez SP - 288 EP - 93 JF - Nature JO - Nature VL - 446 IS - 7133 N2 - Detachment of the three tiny middle ear bones from the reptilian mandible is an important innovation of modern mammals. Here we describe 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. The connected ear and jaw structure is similar to the embryonic pattern in modern monotremes (egg-laying mammals) and placental mammals, but is a paedomorphic feature retained in the adult, unlike in monotreme and placental adults. This suggests that reversal to (or retention of) this premammalian ancestral condition is correlated with different developmental timing (heterochrony) in eutriconodonts. This new eutriconodont adds to the evidence of homoplasy of vertebral characters in the thoraco-lumbar transition and unfused lumbar ribs among early mammals. This is similar to the effect of homeobox gene patterning of vertebrae in modern mammals, making it plausible to extrapolate the effects of Hox gene patterning to account for homoplastic evolution of vertebral characters in early mammals. SN - 1476-4687 UR - https://www.unboundmedicine.com/medline/citation/17361176/A_new_eutriconodont_mammal_and_evolutionary_development_in_early_mammals_ L2 - https://doi.org/10.1038/nature05627 DB - PRIME DP - Unbound Medicine ER -