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Joanusaurid: Difference between revisions
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Joanusauroids share certain distinctive features, one of which is a triangular-shaped pubic boot. Joanusauroids have 3 fingers per hand, with the second and third digit being approximately equal in length. The femur is larger than the tibia. Another defining feature of joanusauroids is that the chevron bases on their tails have anterior and posterior bone growth. The body of joanusauroids can reach up to 10 meters in length; the length of the body from the tail to the hip is between 54% and 62% of the total body length, and the length of the body from the head to the hip is between 38% and 46% of the total body length. Joanusauroids scaled their limbs relative to their body in a way similar to how other large theropods, like the [[Caphirosaurid|caphirosaurids]], did. During the Cretaceous, some joanusauroids grew to sizes similar to those of the largest [[Caphirosaurid|caphirosaurids]]. A notable example is the {{wpl|Late Cretaceous}} ''[[Levaretyrannus]]'' which is thought to have rivaled even ''[[Caphirosaurus]]'' in size. | Joanusauroids share certain distinctive features, one of which is a triangular-shaped pubic boot. Joanusauroids have 3 fingers per hand, with the second and third digit being approximately equal in length. The femur is larger than the tibia. Another defining feature of joanusauroids is that the chevron bases on their tails have anterior and posterior bone growth. The body of joanusauroids can reach up to 10 meters in length; the length of the body from the tail to the hip is between 54% and 62% of the total body length, and the length of the body from the head to the hip is between 38% and 46% of the total body length. Joanusauroids scaled their limbs relative to their body in a way similar to how other large theropods, like the [[Caphirosaurid|caphirosaurids]], did. During the Cretaceous, some joanusauroids grew to sizes similar to those of the largest [[Caphirosaurid|caphirosaurids]]. A notable example is the {{wpl|Late Cretaceous}} ''[[Levaretyrannus]]'' which is thought to have rivaled even ''[[Caphirosaurus]]'' in size. | ||
Other similarities across all joanusauroids include the structure of their hind limb and pelvis. The pelvis in particular is thought to be designed to reduce stress regardless of body size. In particular, the way the femur is inclined reduces the bending and torsion stress. Furthermore, like other animals with tails, joanusauroids possess a caudofemoralis longus (CFL) muscle that allowed them to flex theirs. Larger joanusauroids are found to have a lower CFL muscle-to-body-mass proportion | Other similarities across all joanusauroids include the structure of their hind limb and pelvis. The pelvis in particular is thought to be designed to reduce stress regardless of body size. In particular, the way the femur is inclined reduces the bending and torsion stress. Furthermore, like other animals with tails, joanusauroids possess a caudofemoralis longus (CFL) muscle that allowed them to flex theirs. Larger joanusauroids are found to have a lower CFL muscle-to-body-mass proportion than smaller joanusauroids. | ||
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 ''{{wpl|Stegosaurus}}'', [[Gabion Natural History Museum]]]] | [[File:Allosaurus_attacks_Stegosaurus.jpg|thumb|''[[Joanusaurus]]'' and ''{{wpl|Stegosaurus}}'', [[Gabion Natural History Museum]]]] | ||