dinosaurs;
cranial ontogeny;
Triceratops;
Late Cretaceous;
D O I:
10.1098/rspb.2006.3643
中图分类号:
Q [生物科学];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
This is the first cranial ontogenetic assessment of Triceratops, the well-known Late Cretaceous dinosaur distinguished by three horns and a massive parietal-squamosal frill. Our analysis is based on a growth series of 10 skulls, ranging from a 38 cm long baby skull to about 2 m long adult skulls. Four growth stages correspond to a suite of ontogenetic characters expressed in the postorbital horns, frill, nasal, epinasal horn and epoccipitals. Postorbital horns are straight stubs in early ontogeny, curve posteriorly in juveniles, straighten in subadults and recurve anteriorly in adults. The posterior margin of the baby frill is deeply scalloped. In early juveniles, the frill margin becomes ornamented by 17-19 delta-shaped epoccipitals. Epoccipitals are dorsoventrally compressed in subadults, strongly compressed and elongated in adults and ultimately merge onto the posterior frill margin in older adults. Ontogenetic trends within and between growth stages include: posterior frill margin transitions from scalloped to wavy and smooth; progressive exclusion of the supraoccipital from the foramen magnum; internal hollowing at the base of the postorbital horns; closure of the midline nasal suture; fusion of the epinasal onto the nasals; and epinasal expansion into a morphologically variable nasal horn. We hypothesize that the changes in horn orientation and epoccipital shape function to allow visual identity of juveniles, and signal their attainment of sexual maturity.
机构:
Amer Museum Nat Hist, Div Vertebrate Zool Mammal, New York, NY 10024 USA
Consejo Nacl Invest Cient & Tecn, Buenos Aires, DF, Argentina
Univ Nacl Tucuman, Programa Invest Biodiversidad Argentina, Fac Ciencias Nat, RA-4000 San Miguel De Tucuman, Tucuman, Argentina
Univ Nacl Tucuman, IML, RA-4000 San Miguel De Tucuman, Tucuman, ArgentinaAmer Museum Nat Hist, Div Vertebrate Zool Mammal, New York, NY 10024 USA
Giannini, Norberto P.
Segura, Valentina
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机构:
Consejo Nacl Invest Cient & Tecn, Buenos Aires, DF, Argentina
Museo Argentino Ciencias Nat Bernardino Rivadavia, Buenos Aires, DF, ArgentinaAmer Museum Nat Hist, Div Vertebrate Zool Mammal, New York, NY 10024 USA
Segura, Valentina
Isabel Giannini, Maria
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机构:
Univ Nacl Tucuman, Fac Ciencias Exactas & Tecnol, Dept Matemat, RA-4000 San Miguel De Tucuman, Tucuman, ArgentinaAmer Museum Nat Hist, Div Vertebrate Zool Mammal, New York, NY 10024 USA
Isabel Giannini, Maria
Flores, David
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h-index: 0
机构:
Consejo Nacl Invest Cient & Tecn, Buenos Aires, DF, Argentina
Museo Argentino Ciencias Nat Bernardino Rivadavia, Buenos Aires, DF, ArgentinaAmer Museum Nat Hist, Div Vertebrate Zool Mammal, New York, NY 10024 USA