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 You are here: Social Behaviour >Courtship
 
Courtship

Courtship allows females (and sometimes males) to select their mates based on the potential mates “fitness”. Males often demonstrate this by using visual displays and/or by fighting rival males for the right to mate with females. Such displays and fighting may also occur during territorial disputes.


Horns and Frills
Ceratopsians had a wide range of head morphologies and most of this variation is in the horns and frills of these animals. The horns are likely to have been used in combat between males between females and possibly territory just like the horns of antelope today. The variation in horn morphology throughout the ceratopsian group may have been due to different styles of fighting in different species. Those with large brow horns and a smaller nasal horn, such as Triceratops, may have locked their horns together and wrestled with each other like modern red deer and some chameleons do.

The frills of ceratopsians could have been used as visual displays, perhaps used as displays of strength between males prior to combat. Strength assessing displays can be seen in red deer; in this case fights usually start only if males are similarly matched. Frills in ceratopsians could be extremely large as in Torosaurus or heavily ornamented as in Styracosarus. As in horn morphology the variation in frill shape and size in the ceratopsians may reflect different forms of display and combat and would have also allowed recognition between individuals of the same species.


Boneheads
The dome-shaped skull roofs of pachycephalosaurs were reinforced with thickened bone which in some cases was over 20cm thsick. The purpose of these hardened skulls is commonly believed to have been for fights between males, evidence for this comes from the dimorphism of skulls which are thicker in some individuals but not in others. Such fights are likely to have been over females and possibly territory. These fights may have been head to head with the backbone held horizontally to dissipate the force of the impact down the body.


Crests
As in ceratopsians the hadrosaurs exhibit a wide range of head morphologies, in this case however the variation is in crests rather than horns and frills. Sexual dimorphism of crests is apparent, with male hadrosaurs having significantly larger crests. Juveniles had rather undeveloped crests. This suggests that one of the functions of crests was as sexual display structures, they may well have been brightly coloured in males to attract females, like the feathers of many birds are brightly coloured for mate attraction today. The crests also contain elongated and elaborated nasal passages which could have acted as resonance chambers, producing sound like a wind instrument. As males and females had different crests the sounds they produced would have been different and it is possible that males added an auditory display to the visual one during courtship. As in the case of ceratopsian frills, hadrosaur crests would have been an excellent way for individuals to identify others of the same species. The sounds produced from the crests would have allowed auditory as well as visual discrimination.

 

References;
J.O. Farlow, P. Dodson, The Behavioural Significance of Frill and Horn Morphology in Ceratopsian Dinosaurs, Evolution, Vol. 29 (1975) 353-361.
B. Cox, Fossilised Fury, Nature, Vol. 260 (1976) 748-749.
M.J. Benton, Vertebrate Palaeontology 3ed. Blackwell Publishing, (2005) pgs 209-216.

 


 
 
     
© 2008 Earth Sciences, University of Bristol