Joanusaurid: Difference between revisions
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In addition to body similarities, joanusauroids are also united by certain skull features. Early joanusauroids had ornamental head crests on top of their skulls as tools of socio-sexual display. These head crests would go on to evolve into ridges over the eyes of the later true joanusauridae. Some of the other defining skull features include a smaller mandibular fenestra, a short quadrate bone, and a short connection between the braincase and the palate. Joanusauroid skulls are about 2.5 to 3 times longer than they are tall. Their narrow skull along with their serrated teeth allow joanusauroids to better slice flesh off of their prey. | In addition to body similarities, joanusauroids are also united by certain skull features. Early joanusauroids had ornamental head crests on top of their skulls as tools of socio-sexual display. These head crests would go on to evolve into ridges over the eyes of the later true joanusauridae. Some of the other defining skull features include a smaller mandibular fenestra, a short quadrate bone, and a short connection between the braincase and the palate. Joanusauroid skulls are about 2.5 to 3 times longer than they are tall. Their narrow skull along with their serrated teeth allow joanusauroids to better slice flesh off of their prey. | ||
==Paleobiology== | ==Paleobiology== | ||
[[File:Allosaurus_attacks_Stegosaurus.jpg|thumb|''Joanusaurus'' and ''Stegosaurus'', [[Gabion Natural History Museum]]]] | [[File:Allosaurus_attacks_Stegosaurus.jpg|thumb|''[[Joanusaurus]]'' and ''{{wpl|Stegosaurus}}'', [[Gabion Natural History Museum]]]] | ||
Multiple severe injuries have been found on joanusauroid remains, which implies that joanusauroids were frequently in dangerous situations and supports the hypothesis of an active, predatory lifestyle. Despite the multitude of injuries, only a few of those injuries show signs of infection (a notable exception being the ''[[Joanusaurus]]'' [[Joanusaurus#Big_Yon|Big Yon]]). For those injuries that did become infected, the infections were usually local to the site of the injury, implying that the joanusauroid immune response was able to quickly stop any infection from spreading to the rest of the body. This type of immune response is similar to modern reptilian immune responses; reptiles secrete fibrin near infected areas and localize the infection before it can spread via the bloodstream. | Multiple severe injuries have been found on joanusauroid remains, which implies that joanusauroids were frequently in dangerous situations and supports the hypothesis of an active, predatory lifestyle. Despite the multitude of injuries, only a few of those injuries show signs of infection (a notable exception being the ''[[Joanusaurus]]'' [[Joanusaurus#Big_Yon|Big Yon]]). For those injuries that did become infected, the infections were usually local to the site of the injury, implying that the joanusauroid immune response was able to quickly stop any infection from spreading to the rest of the body. This type of immune response is similar to modern reptilian immune responses; reptiles secrete fibrin near infected areas and localize the infection before it can spread via the bloodstream. | ||
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Although the remains of other large theropods like [[Caphirosaurid|caphirosaurids]] bear evidence of fighting within their species and with other predators, the remains of joanusauroids do not bear much evidence of injuries from theropod combat. Most notably, despite a good fossil record, joanusauroid skulls lack the distinctive face-biting wounds that are common in [[Caphirosaurid|caphirosaurids]] skulls, leaving open the question of if joanusauroids engaged in interspecies and intraspecies fighting. Joanusauroid remains are also often found in groups, which implies social behavior. While there are alternative explanations for the groupings, like predator traps or habitat reduction due to drought, the frequency of finding joanusauroid remains in groups supports the social animal theory. As social animals, joanusauroids would share the burden of hunting, allowing injured members of the pack to recover faster. | Although the remains of other large theropods like [[Caphirosaurid|caphirosaurids]] bear evidence of fighting within their species and with other predators, the remains of joanusauroids do not bear much evidence of injuries from theropod combat. Most notably, despite a good fossil record, joanusauroid skulls lack the distinctive face-biting wounds that are common in [[Caphirosaurid|caphirosaurids]] skulls, leaving open the question of if joanusauroids engaged in interspecies and intraspecies fighting. Joanusauroid remains are also often found in groups, which implies social behavior. While there are alternative explanations for the groupings, like predator traps or habitat reduction due to drought, the frequency of finding joanusauroid remains in groups supports the social animal theory. As social animals, joanusauroids would share the burden of hunting, allowing injured members of the pack to recover faster. | ||
==See also== | ==See also== | ||
*''[[Joanusaurus]]'' | *''[[Joanusaurus]]'' | ||