Compare/Contrast

• Comp/Cont: apophyses

  In reptiles the apophyses are better derived to support lateral stability required in crawling locomotion while in mammals there is greater diversity in apophyses adaptations to support their diverse modes of locomotion. For example, Reptiles evolved for climbing may exhibit longer spinous processes. Meanwhile a mammal that main form of locomotion is running would have more shorter and vertical spinous processes.  In both taxa, the apophyses do serve as an attachment points for muscles and ligaments.
• Comp/Cont: arboreal locomotion

  Mammals are able to swing, leap, and walk through trees, making them an example as animals with arboreal locomotion. They are able to climb trees to sleep and hide their prey. Arboreal birds are able to fly through and hop between the branches of trees in search for food. 
• Comp/Cont: autopodium

  Dolphin carpals are short in height but wide in length to help it propel forward and steer while swimming. Metalcarpals and phalanges are also thicker and closer to allowing the dolphin to bend its flipper up and down.

  Bat carpals are much shorter in length making it look rounder, which helps it control its wings for flight and to grab things. Metacarpals and phalanges are thinner and spread out along the wing allowing bending their wings in certain motions for flight and tucking their wings. 
• Comp/Cont: bicipital

  In most tetrapods, the ribs are bicipital, or they connect to the vertebrea in two different locations. Certain reptiles have a fused fusion of the parapophysis and diapophysis and connect at only one point. 
• COMP/CONT calcaneus

  When thinking of the structure of the calcaneus, what comes to mind is that the heel bone is lying flat on the ground. For example, the image to the left shows a rat’s foot, the calcaneus rests flesh with the rest of the foot to provide balance and support of the hind legs. On the other hand, in elephants, the calcaneus bone is elevated on fatty tissues under the foot, similar to a woman’s foot in a dress heel. The elephants foot holds this unique shape due to their body weight and the varying terrain when they’re walking. 
• COMP/CONT capitulum

  All vertebrates that have forelimbs no matter the shape, have the same set of bones. Birds have a humerus and radius, thus they have a capitulum which connects the humerus and radius. Lizards also have a humerus and radius along with the capitulum connection. The capitulum plays a significant role in the pivoting motion for all these vertebrates. 
• COMP/CONT caracoid

  The caracoid in lizards is connected to the scapula and the sternum as their legs are positioned outward from their body instead of right below, so they need some extra connection to support their arms. On the other hand, mammals' arms, say a dog, are positioned directly below their body so the caracoid is now a reduced bony process that doesn't need to connect to the sternum.
• COMP/CONT carpal

  In quadrupedal mammals, carpal bones tend to be arranged in two rows with eight carpal bones. This allows for flexibility in locomotion and acts as a mechanisms to support the mammals weight. Birds have different modifications as bipedal animals with their carpals having greater fusion. This fusion assist them with supporting the wings during flight. In both taxa the carpal assist with movement but are modified to the taxa's specific mode of locomotion.
• COMP/CONT caudal fin

  A tuna fish has a lunate caudal fin which, when combined with other aspects of the body (like a small caudal peduncle), allows the tuna to swim fast to capture prey. Meanwhile, a shark has a heterocercal caudal fin to help with lift as it swims due to their large body mass and lack of a swim bladder.
• COMP/CONT ceratotrichia

  Ceratotrichia in sharks are found to be more complex as sharks need to have more control and maneuverability in different marine environments. Bichirs have a simpler ceratotrichia due to their smaller size and their simpler swimming mechanisms. 
• COMP/CONT cheiropterygium

  In amphibians, the cheiropterygia are typically used for swimming and are often webbed for better propulsion through water. While in bats, their cheiropterygium limbs are used for flight. It allows for complex adjustments in wing shape and surface area during flight that support their need to perform unique aerial maneuvers.
• COMP/CONT chiridium

  Tetrapods throughout all taxa generally have the same basic anatomy for chiridium although the bone shapes and sizes may very in the limbs. The anatomay of a reptile's chiridium includes bones such as the forarm bones (radius and ulna), humerus, and metacarpals. Where in mammals these bones although may appear different are still present and used for the same function. 
• COMP/CONT clavicle

  While birds have a fused clavicle called a furcula that serves to strengthen the skeleton for flight. While dogs have a mostly cartilage clavicle that not really connected and this is due to not limit movement when the animal is running.
• COMP/CONT coracoid

  The coracoid in mammals holds the function of stabilization for the shoulder joint. In birds, the coracoid serves a major role in supporting the muscles during flight. 
• COMP/CONT crutotarsal joint

  Found in crocodiles and in phytosaurus, this gives crocodiles a funny walk due to the ankle rotation between the proximal and medial ankle bone. This allosw them to have 2 different ways of movement.  Compared to birds which have a mesotaral ankle which their posture. 
• COMP/CONT cursorial locomotion

  Some mammals and birds have the adaption of cursorial locomotion that allows the organism to increase their speed due to the reduced retractive-protractive cycle. While mammals rely on the femur, tibia, and metatarsus for this motion, cursorial birds depend on the tibiotarsus and tarsometatarsus segment in their hind limbs.
• COMP/CONT digitigrade

  Digitigrade vertebrates are typically mammals, like dogs, cats, and hyenas. The metacarpals and metatarsals are elongated which gives their heel and ankle an elevated position which helps them run and jump faster. Other vertebrates that move this way are birds, which use their digits to grasp their perch or prey. Flightless birds like emus use their digits to run, jump, and kick as well.
• COMP/CONT digits

  Raccoons have five digits on each paw that help them grasp food and to climb. In contrast, ducks have three digits that are webbed together and they have a hind toe. The function of the webbed digits to help them move through water. 
• COMP/CONT diphyceral tail

  Diphycercal tails can be seen in lungfish although an interesting thing is that they almost entirely don't use their tail at all when moving on land, instead they use trunk muscles. Their diphycercal tails help them to propel themselves when they are suspended in water. Modern bony fish also contain diphycercal tails but only in their larval stages, as they grow and mature they gain a homocercal tail.
• COMP/CONT episternal cartilage

  In most mammals it acts as a stabilizing force to the sternoclavicular joints however in birds due to the fused calvacal /wishbone
• COMP/CONT femur

  Mammals and reptiles both have femurs in their hindlegs. The femur bone is only located in the hindlegs and not the front legs. Most mammals use the femur bone to help with walking. Some even use it to jump. 
• COMP/CONT fibula

  In canines, the hind limbs contain the fibula bone, separate from other bones. The fibula bone in canines is weaker and not as  functional. The fibula and a few other bones are fully fused in adult frogs that are extant. The tibiofibula, a compound structure that functions as an extra limb segment, was created when the tibia and fibula fused together in extant frogs.  However, the fibula of both these groups is still slender and light weight to aid in mobility. 
• COMP/CONT fossorial locomotion

  Many mammals are adapted for fossorial locomotion, like moles. They have large front limbs and claws that help them move dirt. They also have reduced hindlimbs. There are some reptiles that are also adapted for fossorial locomotion, like in the family Amphisbaena. However, they don't have large claws. Instead, their skulls are heavily ossified and act as shovels. One species within the Amphisbaena has retained the front limbs, but most have lost all limbs for their fossorial lifestyle. Both moles and limbless lizards have reduced eyes for life underground. 
• COMP/CONT: furcula

  It is found in most bird species but it is absent in some. For example, in owls or toucans the furcula bone is absent while in falcons and cranes they have a large furcula. Although, these birds lack the furcula they can still fly perfectly fine but the difference is that in these larger/stronger flyers the furcula is large and hollow allowing them to have more flexibility. Also, the furcula helps with respiration by allowing air to go through the air sacs. 
• COMP/CONT: homocercal tail

  In salmon the homocercal tail is symmetrical and used to help swim through the water and locomotion while in bass the tail is still considered homocercal but it is not fanned out like the salmon, it tapers down to meet in the middle of the tail and aids in locomotion
• COMP/CONT: humerus

  In amphibians such as frogs the humerus does not bind to the radius and ulna like in mammals, the radius and ulna are fused so the humerus is not structured to connect to two bones. Its structure is adapted for the use of burrowing, swimming, and moving on land. The humerus in birds are much more fragile and light compared to amphibians as they are built for flying, they are connected to the ulna and radius but those bones are not fused like in amphibians.
• COMP/CONT ilium

  The main function of the Ilium is to help animals with weight bearing since it supports the spine as the body stays upright. However, it does have some other functions within different taxa. In birds, it helps with the muscle attachment of the tail and also help maintain a healthy flying posture. Within mammals, they help with locomotion, protection, and pelvic control.
• COMP/CONT innominate bones

  In fish, the innominate bones are used to support the pelvic fins and are not connected to the verebral calumn. The pelvic fins are found under the fish, typiclally below the pectoral fins, and lack an ilium. However in amphibians such as frogs, the ilium is present and runs the length of the urostyle. The Ischium and pubis are underneath and all three are fused and connected to the acetebulum, which is a socked to hold the femur.
• COMP/CONT interclavicle

  The Tuatara used the interclavicle for support and stability of the shoulder girdle which helps it in activities such as burrowing. Archaeopteryx have an interclavicle as well but for flight. It was used as well to provide support for the shoulder girdle, but instead to help the bird complete wing movements during flight.
• COMP/CONT ischium

  The function of the ishchium bone is for leg mobility and balance. This is seen in all the different animals, but it can vary in uses between different taxa. The ischium within reptiles is thinner in comparison to those of mammals as they do not endure as much weight in comparison to mammals who have a larger or extended ischium bone.
• COMP/CONT lepitotrichia

  In fish, these structures help to support the fin as well as helping the fish adapt to the flow of water when swimming. In comparison, birds use their wings to fly and move them to be more or less aerodynamic. Although their structures may look different, they have similar functions: movement. 
• COMP/CONT manus

  The manus is very diverse in mammals, spanning from having webbing for aquatic mammals to hands for aeorborial mammals, while fish don't have them at all. 
• COMP/CONT median fins

  Medial fins are specific to fish, as they are the only vertebrates with "true" fins. These fins may vary from species, such as for stablization of swimming (red drum) to being the primary force of locolotion (mola mola) However, other taxa have medial structures, but they do not compare to those of fish.
• COMP/CONT mesopterygium

  The mesoterygium is a very odd trait as it only seems to be found in fish. As mentioned before it helps to "complete" the find and fill out its structure. From the extent of my research, no other taxa possesses mesopterygia.
• COMP/CONT metapterygium

  The metapterygium is located in fish such as sharks and rays however bird do not have this feature. They have something similar called alula located on the edge of their wings to control airflow for flight.
• COMP/CONT metatarsals

  For birds the metatarsals are all one structure known as tarsometatarsus. While, pigs have four metatarsals two are used for supporting the weight of the animal and the other two are smaller and do not touch the ground. 
• COMP/CONT patella

  Birds have adapted and their patella is known as patelloid. Instead of a flat bone like in mammals it is a sesamoid bone in birds. They both have similar functions when it comes to helping with the extension of the leg. 
• COMP/CONT: pectoral girdle

  In fish, the pectoral girdle helps support the pectoral fins while in birds, it supports the wing bones.
• COMP/CONT pelvic girdle

  In mammals and some amphibians the pelvic girdle consists of three bones which are the ilium, ischium and pubis. The main function of the pelvic girdle is to support the weight of the body within different postures. In mammals the structure of the pelvic girdle is designed for bipedal or quadrupedal movement. In frogs, their pelvic girdle is more elongated and V-shaped which helps for jumping and swimming. Their pelvic girdle is less complex and less fused which aids in flexibility for their environment. 
• COMP/CONT pentadactylous

  Most reptiles, mammals, and birds have pentadactylous limbs with 5 digits but originally, it evolved from paired fins on fish but is not found on fish today.