Exoskeleton Terms

Exoskeleton of Fishes

"The _ is mainly dermal formed by the dermis beneath a thin epidermis."

Placoid Scales

"_ are tooth like with a basal bony plate and a spine of dentine capped with enamel like material."

Cosmoid Scales

"_ have three layers and represent the fusion of earlier placoid elements into broad dermal plates."

Ganoid Scales

"_ have an outer ganoin layer that is enamel like over a bony base and are hard shiny and rhomboid with peg and socket joints that give flexibility."

Cycloid Scales

"_ have smooth edges and are thin overlapping and flexible with growth rings that reveal age."

Ctenoid Scales

"_ have toothed posterior edges and are thin overlapping and flexible with growth rings that reveal age."

Dermal Fin Rays

"_ support fins and exist in several structural types."

Ceratotrichia

"_ are fibrous unjointed fin rays found in sharks."

Actinotrichia

"_ are embryonic fibers that support developing fins."

Lepidotrichia

"_ are ossified jointed fin rays found in teleosts."

Camptotrichia

"_ are transitional fin rays found in lungfishes."

Exoskeleton of Turtles

"The _ consists of two main parts the carapace dorsal shell and the plastron ventral shell."

Carapace

"The _ forms the dorsal surface of the turtle shell and is connected to the plastron by bridges."

Epidermal Scutes

"_ are large thin horny plates that cover the outer surface of the carapace and are epidermal in origin."

Neural Scutes

"_ form the median row of scutes along the dorsal midline of the carapace."

Costal Scutes

"_ are the lateral rows of scutes on each side of the carapace."

Marginal Scutes

"_ are small scutes forming the border around the shell."

Nuchal Scute

"The _ is the anterior median scute of the carapace."

Pygal Scutes

"The _ are the two posterior median scutes of the carapace."

Bony Layer of Carapace

"The _ is composed of heavy dermal plates joined by jagged sutures and fused to the vertebrae and ribs."

Nuchal Plate

"The _ is a large anterior bony plate at the front of the carapace."

Vertebral Plates

"The _ are eight neural plates fused to the vertebrae."

Postneural Plates

"The _ are two posterior plates not attached to vertebrae."

Costal Plates

"The _ are eight plates on each side of the carapace each attached to a rib."

Marginal Plates

"The _ form the edge of the carapace and include paired marginal plates and a single posterior pygal plate."

Plastron

"The _ forms the ventral surface of the turtle shell and is covered by horny scutes arranged in six pairs."

Gular Scutes

"The _ are the most anterior pair of scutes on the plastron."

Humeral Scutes

"The _ are the second pair of scutes on the plastron located behind the gular scutes."

Pectoral Scutes

"The _ are the third pair of scutes on the plastron located behind the humeral scutes."

Abdominal Scutes

"The _ are the fourth pair of scutes on the plastron located behind the pectoral scutes."

Femoral Scutes

"The _ are the fifth pair of scutes on the plastron located behind the abdominal scutes."

Anal Scutes

"The _ are the sixth and most posterior pair of scutes on the plastron."

Inframarginal Scutes

"The _ cover the bridges that connect the plastron and carapace."

Bony Layer of Plastron

"The _ is formed of dermal bony plates joined by jagged sutures."

Epiplastra

"The _ are the anterior pair of bony plates in the plastron."

Entoplastron

"The _ is a single median plate with a posteriorly projecting point located in the plastron."

Hyoplastra

"The _ are the first of three posterior pairs of bony plates in the plastron."

Hypoplastra

"The _ are the second of three posterior pairs of bony plates in the plastron."

Xiphiplastra

"The _ are the third and most posterior pair of bony plates in the plastron."

Exoskeleton of Birds

"The _ is entirely epidermal in origin and has no true dermal plates."

Feathers

"_ are homologous with reptilian scales and are keratinized derivatives of the stratum corneum."

Contour Feathers

"_ determine the body shape and function in flight."

Down Feathers

"_ provide insulation to birds."

Filoplumes

"_ are hairlike sensory feathers in birds."

Bird Scales

"_ are retained on the tarsi and feet of birds."

Claws

"_ are keratinized sheaths that cover the terminal phalanges."

Beak

"The _ is a horny covering over the jaw bones that replaces reptilian teeth."

Exoskeleton of Mammals

"The _ is primarily epidermal and serves for protection temperature control and display."

Hair

"_ is unique to mammals and composed of keratin."

Hair Structure

"The _ root lies in a follicle with a dermal papilla and the shaft projects outward."

Cuticle

"The _ is the outer scaly layer of hair."

Cortex

"The _ contains pigment and provides strength to the hair."

Medulla

"The _ is the central core of the hair and is often hollow."

Mammalian Scales

"_ occur on the tails of some rodents and pangolins."

Armadillo Armor

"The _ consists of epidermal scutes over dermal bony plates forming movable armor."

Mammalian Claws

"_ are curved keratinized sheaths considered the ancestral form."

Nails

"_ are flattened keratinized specializations covering the dorsal surface of the digits."

Hoofs

"_ are thickened keratinized specializations covering the tips of the digits."

True Horns

"_ have a bony dermal core with a keratin sheath as seen in bovids."

Hair Horns

"_ are made of compacted keratin with no bone as seen in the rhinoceros."

Hair Evolution

"_ is not homologous to reptilian scales and likely evolved from epidermal sensory papillae."

Cosmine

“The _ is a dentine like layer.”

Vascular bone

“The middle layer of very _, permeated with blood channels.”

Isopedine

“The inner layer of lamellate bone, or so called as _.”