Giraffes Necks: A Case Study

Decent Essays
Senter (2006) hypothesized that sauropods’ necks were for sexual selection. Senter (2006) studied a similar animal to reach this hypothesis. Senter (2006) studied giraffes’ behaviors and characteristics because of their similarity to sauropods. Previous research on giraffes suggested that their necks were primarily for sexual selection. The characteristics that suggest that sauropods’ and giraffes’ necks were used for sexual selection include; trait dominance in one gender over another, survival cost, and no survival benefit (Senter 2006). Senter (2006) concluded that because of these features, it could be a possibility that sexual selection was the function of sauropods’ necks. Taylor et al (2011) challenged Senter’s (2006) hypothesis. New…show more content…
The new data showed that giraffes’ necks functioned in multiple ways (Taylor et al. 2011) this opposed previous data that suggested that giraffes’ necks were primarily for sexual selection (Senter 2006). Taylor et al (2011) found that rarely do morphological adaptions have one single function and this is true in the case of giraffes and sauropods. Giraffes’ necks have not been proven to be different in length per gender (Taylor et al. 2011) because of this we can rule out dominance of trait in gender (Taylor et al 2011). It has been shown that giraffes do have an advantage in feeding because of their elongated necks and this has been experimentally and observationally studied (Taylor et al. 2011). These are not the only hypotheses to try to explain the function of sauropods’…show more content…
Seymour et al (2009) hypothesized that sauropods kept their necks down instead of raised. Through studying blood circulation systems and how this affects other animals, Seymour et al (2009) found that it would not be possible or difficult for a sauropod to have their neck raised for long periods of time. Seymour et al (2009) estimate that for a sauropod to raise its head nine meters above its heart, would require its heart to generate 750 mm Hg blood pressure as opposed to an average of 100 mm Hg. Even if a sauropod had a large or strong heart, the energy cost of blood circulation would have been an estimated 45% of the animals’ energy consumption (Seymour et al. 2009). Seymour et al (2009) suggest that because of this it would have been energetically inefficient for a sauropod to raise its head to feed on high food sources. In 2010, Christian (2010) challenged this hypothesis with his study of the Euhelopus zdanskyi. Studying the Euhelopus zdanskyi and Brachiosaurus revealed that energy consumption and stress for raising the neck was lower than previously estimated (Christian 2010). This was contrary to what Seymour et al (2009) estimated and it was estimated that walking 100 meters was equivalent to five minutes of high browsing (Christian 2010). Since energy expenditure was not an issue it is a possibility that sauropods raised their necks for long periods of
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