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Biology of the sauropod dinosaurs: the evolution of gigantism.

Sander PM, Christian A, Clauss M, Fechner R, Gee CT, Griebeler EM, Gunga HC, Hummel J, Mallison H, Perry SF, Preuschoft H, Rauhut OW, Remes K, Tütken T, Wings O, Witzel U - Biol Rev Camb Philos Soc (2011)

Bottom Line: Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates.The extensive pneumatization of the axial skeleton resulted from the evolution of an avian-style respiratory system, presumably at the base of Saurischia.An avian-style respiratory system would also have lowered the cost of breathing, reduced specific gravity, and may have been important in removing excess body heat.

View Article: PubMed Central - PubMed

Affiliation: Steinmann Institute, University of Bonn, Germany. martin.sander@uni-bonn.de

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Variation of atmospheric composition(O2, CO2) and body size through time. Each data point is located at the beginning of a stage, starting with the Carnian and ending with the Cretaceous-Tertiary boundary. The variation of body size through time is an extension of the Carrano (2006) data set with femur length as a proxy for body size. Missing data points for body mass are either due to lumping of data from two stages (i.e. the Kimmeridgian and Tithonian) or missing data (i.e. for the Berriasian, Barremian, and Aptian). Body size increases gradually from the Late Triassic to the Late Jurassic, forming a plateau in the Cretaceous. The two sharp drops in body mass in the Early and Late Cretaceous are probably due to a poor terrestrial fossil record at these times. Note the lack of correlation between atmospheric composition and sauropod body mass. CO2content of the atmosphere also determines global temperature, and this graph thus suggests that sauropod body size is not correlated with global temperature variations through time, either. The data for O2 and CO2 levels are from Ward (2006).
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fig08: Variation of atmospheric composition(O2, CO2) and body size through time. Each data point is located at the beginning of a stage, starting with the Carnian and ending with the Cretaceous-Tertiary boundary. The variation of body size through time is an extension of the Carrano (2006) data set with femur length as a proxy for body size. Missing data points for body mass are either due to lumping of data from two stages (i.e. the Kimmeridgian and Tithonian) or missing data (i.e. for the Berriasian, Barremian, and Aptian). Body size increases gradually from the Late Triassic to the Late Jurassic, forming a plateau in the Cretaceous. The two sharp drops in body mass in the Early and Late Cretaceous are probably due to a poor terrestrial fossil record at these times. Note the lack of correlation between atmospheric composition and sauropod body mass. CO2content of the atmosphere also determines global temperature, and this graph thus suggests that sauropod body size is not correlated with global temperature variations through time, either. The data for O2 and CO2 levels are from Ward (2006).

Mentions: All else being equal, would an increased level of atmospheric oxygen allow the evolution of gigantic terrestrial tetrapods? This possibility is suggested by the example discussed above of the uniquely gigantic dragonflies of the Carboniferous (Lighton, 2007). Hengst et al. (1996) explored this hypothesis for sauropod dinosaurs, based on the premise of an oxygen level of 30% or above in the Jurassic atmosphere (Landis et al., 1996). Physically modelling respiration in the Late Jurassic sauropod Apatosaurus, they concluded that the respiratory system of this animal could not have delivered enough oxygen to the tissues at today's oxygen levels. This applied even under the assumption that Apatosaurus had the basal metabolic rate of a reptilian ectotherm. However, the hypothesis of Hengst et al. (1996) is superseded by the likely presence of a bird-like lung in sauropods and the current understanding that oxygen levels were significantly lower in the Jurassic and Cretaceous than today (Gans et al., 1999; Dudley, 1998; Berner, 2006; Berner et al., 2007; see also Fig. 8) or at about the same level (Bergman, Lenton & Watson, 2004; Belcher & McElwain, 2008).


Biology of the sauropod dinosaurs: the evolution of gigantism.

Sander PM, Christian A, Clauss M, Fechner R, Gee CT, Griebeler EM, Gunga HC, Hummel J, Mallison H, Perry SF, Preuschoft H, Rauhut OW, Remes K, Tütken T, Wings O, Witzel U - Biol Rev Camb Philos Soc (2011)

Variation of atmospheric composition(O2, CO2) and body size through time. Each data point is located at the beginning of a stage, starting with the Carnian and ending with the Cretaceous-Tertiary boundary. The variation of body size through time is an extension of the Carrano (2006) data set with femur length as a proxy for body size. Missing data points for body mass are either due to lumping of data from two stages (i.e. the Kimmeridgian and Tithonian) or missing data (i.e. for the Berriasian, Barremian, and Aptian). Body size increases gradually from the Late Triassic to the Late Jurassic, forming a plateau in the Cretaceous. The two sharp drops in body mass in the Early and Late Cretaceous are probably due to a poor terrestrial fossil record at these times. Note the lack of correlation between atmospheric composition and sauropod body mass. CO2content of the atmosphere also determines global temperature, and this graph thus suggests that sauropod body size is not correlated with global temperature variations through time, either. The data for O2 and CO2 levels are from Ward (2006).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045712&req=5

fig08: Variation of atmospheric composition(O2, CO2) and body size through time. Each data point is located at the beginning of a stage, starting with the Carnian and ending with the Cretaceous-Tertiary boundary. The variation of body size through time is an extension of the Carrano (2006) data set with femur length as a proxy for body size. Missing data points for body mass are either due to lumping of data from two stages (i.e. the Kimmeridgian and Tithonian) or missing data (i.e. for the Berriasian, Barremian, and Aptian). Body size increases gradually from the Late Triassic to the Late Jurassic, forming a plateau in the Cretaceous. The two sharp drops in body mass in the Early and Late Cretaceous are probably due to a poor terrestrial fossil record at these times. Note the lack of correlation between atmospheric composition and sauropod body mass. CO2content of the atmosphere also determines global temperature, and this graph thus suggests that sauropod body size is not correlated with global temperature variations through time, either. The data for O2 and CO2 levels are from Ward (2006).
Mentions: All else being equal, would an increased level of atmospheric oxygen allow the evolution of gigantic terrestrial tetrapods? This possibility is suggested by the example discussed above of the uniquely gigantic dragonflies of the Carboniferous (Lighton, 2007). Hengst et al. (1996) explored this hypothesis for sauropod dinosaurs, based on the premise of an oxygen level of 30% or above in the Jurassic atmosphere (Landis et al., 1996). Physically modelling respiration in the Late Jurassic sauropod Apatosaurus, they concluded that the respiratory system of this animal could not have delivered enough oxygen to the tissues at today's oxygen levels. This applied even under the assumption that Apatosaurus had the basal metabolic rate of a reptilian ectotherm. However, the hypothesis of Hengst et al. (1996) is superseded by the likely presence of a bird-like lung in sauropods and the current understanding that oxygen levels were significantly lower in the Jurassic and Cretaceous than today (Gans et al., 1999; Dudley, 1998; Berner, 2006; Berner et al., 2007; see also Fig. 8) or at about the same level (Bergman, Lenton & Watson, 2004; Belcher & McElwain, 2008).

Bottom Line: Scaling relationships between gastrointestinal tract size and basal metabolic rate (BMR) suggest that sauropods compensated for the lack of particle reduction with long retention times, even at high uptake rates.The extensive pneumatization of the axial skeleton resulted from the evolution of an avian-style respiratory system, presumably at the base of Saurischia.An avian-style respiratory system would also have lowered the cost of breathing, reduced specific gravity, and may have been important in removing excess body heat.

View Article: PubMed Central - PubMed

Affiliation: Steinmann Institute, University of Bonn, Germany. martin.sander@uni-bonn.de

Show MeSH
Related in: MedlinePlus