Comparative anatomy of selected basal ceratopsian dentitions

2009 ◽  
Vol 46 (6) ◽  
pp. 425-439 ◽  
Author(s):  
Kyo Tanoue ◽  
Hai-Lu You ◽  
Peter Dodson
Keyword(s):  
Comparative Anatomy ◽  
Tooth Size ◽  
Evolutionary Trends ◽  
Tooth Position ◽  
Wear Facet

The dental structure of basal ceratopsians is described. Evolutionary trends in maxillary and dentary teeth of basal ceratopsians include decrease and possible loss of enamel on the occluding side of tooth crowns, increase in the angle of wear facet, development of a prominent primary ridge and deep indentations on mesial and distal sides of the primary ridge, and increase in tooth size in neoceratopsians. Premaxillary teeth in the basalmost ceratopsian Yinlong and basal neoceratopsian Archaeoceratops oshimai exhibit wear facets and denticles along the carina, which imply use for feeding. Maxillary and dentary teeth of basal ceratopsians were probably not as effective in feeding as those in ceratopsids because of the relatively less prominent primary ridges. Some dental characters can be used to identify taxon and tooth position of isolated basal ceratopsian teeth.

Diversity of brood chambers in calloporid bryozoans (Gymnolaemata, Cheilostomata): comparative anatomy and evolutionary trends

Zoomorphology ◽  
2008 ◽  
Vol 128 (1) ◽  
pp. 13-35 ◽  
Author(s):  
Andrew N. Ostrovsky ◽  
Claus Nielsen ◽  
Norbert Vávra ◽  
Ekaterina B. Yagunova
Keyword(s):  
Comparative Anatomy ◽  
Evolutionary Trends

Dental Arch Asymmetry, Fluctuating Dental Asymmetry, and Dental Crowding: A Comparison of Tooth Position and Tooth Size Between Antimeres

2008 ◽  
Vol 14 (2) ◽  
pp. 157-165 ◽  
Author(s):  
Matthew W. Sprowls ◽  
Richard E. Ward ◽  
Paul L. Jamison ◽  
James K. Hartsfield
Keyword(s):  
Dental Arch ◽  
Tooth Size ◽  
Tooth Position ◽  
Dental Crowding

Sri Lankan Cleft Lip and Palate Study Model Analysis: Clefts of the Secondary Palate

1993 ◽  
Vol 30 (2) ◽  
pp. 227-230 ◽  
Author(s):  
Andrew Mccance ◽  
David Roberts-Harry ◽  
Martyn Sherriff ◽  
Michael Mars ◽  
William J.B. Houston
Keyword(s):  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Model Analysis ◽  
Control Group ◽  
Tooth Size ◽  
Sri Lankan ◽  
Control Groups ◽  
Secondary Palate ◽  
Comparable Control ◽  
And Control

The study models of a group of adult Sri Lankan patients with clefts of the secondary palate were investigated. Tooth-size and arch-dimension comparisons were made with a comparable control group. Significant differences were found between the cleft and control groups in tooth sizes, chord lengths, and arch widths. The cleft group dimensions were generally smaller than those of the control group. Overjets were larger in the cleft group.

Floral Vascular Comparative Anatomy ofStellaria mediaandMyosoton aquaticumand its Systematic Significance

2013 ◽  
Vol 31 (6) ◽  
pp. 525
Author(s):  
Zu-Ren LI ◽  
Nan HU ◽  
Ji-Gang YANG ◽  
Bing YANG ◽  
Hai-Min LIAO
Keyword(s):  
Comparative Anatomy ◽  
Systematic Significance

Effect of Contact Ratio on Spur Gear Dynamic Load With No Tooth Profile Modifications

1996 ◽  
Vol 118 (3) ◽  
pp. 439-443 ◽  
Author(s):  
Chuen-Huei Liou ◽  
Hsiang Hsi Lin ◽  
F. B. Oswald ◽  
D. P. Townsend
Keyword(s):  
Dynamic Load ◽  
Spur Gear ◽  
Tooth Size ◽  
Contact Ratio ◽  
Gear Dynamics ◽  
Wide Range ◽  
Gear Contact ◽  
Center Distance ◽  
Selection Of ◽  
Better Than

This paper presents a computer simulation showing how the gear contact ratio affects the dynamic load on a spur gear transmission. The contact ratio can be affected by the tooth addendum, the pressure angle, the tooth size (diametral pitch), and the center distance. The analysis presented in this paper was performed by using the NASA gear dynamics code DANST. In the analysis, the contact ratio was varied over the range 1.20 to 2.40 by changing the length of the tooth addendum. In order to simplify the analysis, other parameters related to contact ratio were held constant. The contact ratio was found to have a significant influence on gear dynamics. Over a wide range of operating speeds, a contact ratio close to 2.0 minimized dynamic load. For low-contact-ratio gears (contact ratio less than two), increasing the contact ratio reduced gear dynamic load. For high-contact-ratio gears (contact ratio equal to or greater than 2.0), the selection of contact ratio should take into consideration the intended operating speeds. In general, high-contact-ratio gears minimized dynamic load better than low-contact-ratio gears.

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