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An illustration of the skeletal fossil of Archaeopteryx, the earliest and most primitive bird known. Archaeopteryx lived in the late Jurassic Period around 155–150 million years ago, in what is now southern Germany during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now.

Archaeopteryx Fossil

An illustration of the skeletal fossil of Archaeopteryx, the earliest and most primitive bird known.…

An illustration of an Ichthyosaurus skeleton. Ichthyosaurus is an extinct genus of ichthyosaur from the Early Jurassic (Hettangian - Sinemurian) of Europe (Belgium, England and Germany). It is among the best known ichthyosaur genera, with the Order Ichthyosauria being named after it. Ichthyosaurus was the first complete fossil to be discovered in the early 1800's by Mary Anning in England.

Archaeopteryx Skeleton

An illustration of an Ichthyosaurus skeleton. Ichthyosaurus is an extinct genus of ichthyosaur from…

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish don't have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems. They digest using the gastrodermal lining of the gastrovascular cavity, where nutrients are absorbed. They do not need a respiratory system since their skin is thin enough that the body is oxygenated by diffusion. They have limited control over movement and mostly free-float, but can use the hydrostatic skeleton of the water pouch to accomplish vertical movement through pulsations of the disc-like body.

Jellyfish

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish…

An illustration of the skeleton of a kangaroo's right hind foot.

Kangaroo Foot

An illustration of the skeleton of a kangaroo's right hind foot.

The skeleton of a bird. Labels: a, radius and ulna; b, dorsal vertebrae; c, sacrum and pelvis; g, ploughshare bone; h, tibia; i, metatarsus; d, furculum; e, carina of the sternum; f, distal phalanx of pectoral limb.

Skeleton of a Bird

The skeleton of a bird. Labels: a, radius and ulna; b, dorsal vertebrae; c, sacrum and pelvis; g, ploughshare…

An illustration of a Diplodocus skeleton and the caudal vertebrae (A and B). Diplodocus is a genus of diplodocid sauropod dinosaur whose fossils were first discovered in 1877 by S. W. Williston. It lived in what is now western North America at the end of the Jurassic Period. Diplodocus is one of the more common dinosaur fossils found in the Upper Morrison Formation, a sequence of shallow marine and alluvial sediments deposited about 150 to 147 million years ago, in what is now termed the Kimmeridgian and Tithonian stages.

Diplodocus

An illustration of a Diplodocus skeleton and the caudal vertebrae (A and B). Diplodocus is a genus of…

Illustration of a dodo bird skeleton. The dodo (Raphus cucullatus) was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about 20 kilograms (44 lb), living on fruit and nesting on the ground.

Dodo Skeleton

Illustration of a dodo bird skeleton. The dodo (Raphus cucullatus) was a flightless bird endemic to…

An illustration of the skeleton of a pezophaps solitarius, part of the dodo family.

Pezophaps Solitarius (Skeleton)

An illustration of the skeleton of a pezophaps solitarius, part of the dodo family.

Corals are marine organisms from the class Anthozoa and exist as small sea anemone-like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.

Coral

Corals are marine organisms from the class Anthozoa and exist as small sea anemone-like polyps, typically…

The skeleton of an elasmosaurus, a dinosaur in the order of plesiosaurs.

Elasmosaurus Skeleton

The skeleton of an elasmosaurus, a dinosaur in the order of plesiosaurs.

"Skeleton and Outline of African Elephant (Elephas or Loxodon africanus). fr, frontal; ma, mandible; ma', malar; fi, "finger" at end of trunk; C, cervical vertebrae; D, dorsal vertebrae; D, dorsal vertebrae; pe, pelvis; sc, scapula; st, sternum; hu, humerus; ul, ulna; ra, radius; mc, metacarpus; fe, femur; pat, patella; tib, tibia; fib, fibula; met, metatarsus." -Whitney, 1911

African Elephant Skeleton

"Skeleton and Outline of African Elephant (Elephas or Loxodon africanus). fr, frontal; ma, mandible;…

"Anterior View, Distal End, of Right Humerus of a Man. H, humerus; epc, epicondyle, or external supracondyloid protuberance; ept, epitrochlea, or internal supracondyloid protuberance; cp, capitellum, or convex articular suface for head of radius; tr, trochlea, or transversely concave articular surface for the ulna; epc and cp are together the ectocondyle, and ept and tr are together the entocondyle." -Whitney, 1911

Humerus

"Anterior View, Distal End, of Right Humerus of a Man. H, humerus; epc, epicondyle, or external supracondyloid…

"Right Femur of a Youth. E, E, epiphyses; gtr, ltr, greater and lesser trochanter; h, head; et, it, external and internal tuberosity; ec, ic, external and internal condyle; n, neck." -Whitney, 1911

Youth Femur

"Right Femur of a Youth. E, E, epiphyses; gtr, ltr, greater and lesser trochanter; h, head; et, it,…

"Epipleurae.-- Thorax, scapular arch, and part of pelvic arch of a bobolink (Dolichonyx oryzivorus). ep, four epipleurae or uncinate processes of as many ribs; pl, pleurapophysial parts of seven ribs; hp, hemapopysial parts of six ribs; v, dorsolumbar vertebrae; st, sternum (the letters are on the carina or keel); m, manubrium sterni; cp, costal process of sternum, bearing f, furcula; ec, epiclidium of furcula; h, hypoclidium of fucula; gl, glenoid fossa, formed by coracoid and scapula; il, ilium; is, ischium; p, pubis; a, acetabulum." -Whitney, 1911

Bobolink Epipleurae

"Epipleurae.-- Thorax, scapular arch, and part of pelvic arch of a bobolink (Dolichonyx oryzivorus).…

"Skeleton of Horse (Equus caballus). fr, frontal bone; C, cervical vertebrae; D, dorsal vertebrae; L, lumbar vertebrae; cd, caudal vertebrae; sc, scapula; pe, pelvis; ma, mandible; hu, humerus; ra, radius; cp, carpus; mc, metacarpus; fe, femur; tib, tibia; ca, calcaneum; tar, tarsus; mt, metatarsus; p, phalanges." -Whitney, 1911

Horse Skeleton

"Skeleton of Horse (Equus caballus). fr, frontal bone; C, cervical vertebrae; D, dorsal vertebrae; L,…

An illustration of Xiphacantha showing the siliceous skeleton.

Xiphacantha

An illustration of Xiphacantha showing the siliceous skeleton.

An illustration of the upper portion of a sponge: p, Pore; s, Subdermal cavity; c1, chief fiver of the skeleton; c2, connecting film. The sponges or poriferans (from Latin porus "pore" and ferre "to bear") are animals of the phylum Porifera. Their bodies consist of an outer thin layer of cells, the pinacoderm and an inner mass of cells and skeletal elements, the choanoderm. Sponges do not have nervous, digestive or circulatory systems. Instead most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, and the shapes of their bodies are adapted to maximize the efficiency of the water flow.

Upper Section of Sponge

An illustration of the upper portion of a sponge: p, Pore; s, Subdermal cavity; c1, chief fiver of the…

Corals are marine organisms from the class Anthozoa and exist as small sea anemone–like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.

Coral

Corals are marine organisms from the class Anthozoa and exist as small sea anemone–like polyps,…

A Cretaceous sponge with silicious skeleton retaining its form. (<em>Ventriculites simplex</em>).

A Cretaceous Sponge

A Cretaceous sponge with silicious skeleton retaining its form. (Ventriculites simplex).

Part of the skeletal structure of a lithisdid silicious sponge.

Jereiea Polystoma

Part of the skeletal structure of a lithisdid silicious sponge.

"Skull of Cat (Felis catus), showing the following bones, viz. : na, nasal; pm, premaxillary; m, maxillary; l, lacrymal; f, frontal; j, jugal; pa, palatine; p, parietal; sq, squamosal; ip, interparietal; so, supra-occipital; eo, exoccipital (the line leads to the occipital condyle); t, tympanic bulla; smf, stylomastoid foramen; mf, mental foramen; c, coronoid process of mandible; ar, ascending ramus of mandible; hr, horizontal ramus of mandible; an, angle of jaw." -Whitney, 1911

Domestic Cat Skull

"Skull of Cat (Felis catus), showing the following bones, viz. : na, nasal; pm, premaxillary; m, maxillary;…

"Anterior View of Human Right Femur. ec, external condyle; etu, external tuberosity; ic, internal condyle; itu, internal tuberosity; ltr, lesser trochanter; gtr, great trochanter; h, head; n, neck." -Whitney, 1911

Anterior View of Human Right Femur

"Anterior View of Human Right Femur. ec, external condyle; etu, external tuberosity; ic, internal condyle;…

"Posterior View of Left Femur of a Horse. h, head; gtr, great trochanter; ttr, third trochanter; ltr, lesser trochanter; p, pit for round ligament; itf, intertrochanteric fossa; d, a depression or fossa; etu, itu, external and internal tuberosities; cc, the two condyles." -Whitney, 1911

Posterior View of Left Femur of Horse

"Posterior View of Left Femur of a Horse. h, head; gtr, great trochanter; ttr, third trochanter; ltr,…

"Skeleton of Fish (Perch). a, intermaxillaries; b, nasal region; c, dentary bone of mandible; d, orbit of eye; e, supraoccipital crest; f, preoperculum; g, g', vertebral column; h, pectoral fin; i, ventral fin; k, first dorsal fin; l, second dorsal fin; m, anal fin; n, n, caudal fin, making a homocercal tail." -Whitney, 1911

Skeleton of Perch

"Skeleton of Fish (Perch). a, intermaxillaries; b, nasal region; c, dentary bone of mandible; d, orbit…

An illustration of coral. Corals are marine organisms from the class Anthozoa and exist as small sea anemone&ndash;like polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton.

Coral

An illustration of coral. Corals are marine organisms from the class Anthozoa and exist as small sea…

An illustration of a whale skeleton.

Whale Skeleton

An illustration of a whale skeleton.

"Third cervical vertebra of Woodpecker (Picus viridis). (Viewed anteriorly.) Ft, vertebrarterial foramen; Ob, upper arch ; Pa, articular process; Psi, haemal spine ; Pt, Pt, the two bars of the transverse process, shewn on one side ancylosed with the cervical rib (R); Sa articular surface of centrum. (From Wieersheim.) A. H. Evans, 1900

The Diagram of a Third Cervical Vertebra of a Woodpecker

"Third cervical vertebra of Woodpecker (Picus viridis). (Viewed anteriorly.) Ft, vertebrarterial foramen;…

"Skeleton of the trunk of a Falcon. Ca, coracoid, which articulates with the sternum (St) at ; Cr, keel of sternum; Fu (Cl), furcula (clavicles); G, glenoid cavity for humerus; S, scapula; Un uncinate process; V, vertebral, and Sp, sternal, portion of rib. (From Wiedersheim.)" A. H. Evans, 1900

The Skeleton of the Trunk of a Falcon

"Skeleton of the trunk of a Falcon. Ca, coracoid, which articulates with the sternum (St) at ; Cr, keel…

"Skeleton of the Limbs and Tail of a Carinate Bird. (The skeleton of the body is indicated by dotted lines.) F, digits; Fi, fibula; HW, carpus; MF, tarsometatarsus; MH, carpometacarpus; OA, humerus; OS, femur; Py, pygostyle; R, coracoid; Ul, ulna; Sch, scapula; St, sternum, with its keel (Cr); T, tibiotarsus; Rd, radius; Z, Z, digits of foot. (From Wiedersheim.)" A. H. Evans, 1900

Skeleton of the Limbs and Tail of a Carinate Bird

"Skeleton of the Limbs and Tail of a Carinate Bird. (The skeleton of the body is indicated by dotted…

"Skull of a Wild Duck (Anus boscas), from the side. ag, Angular; als, alisphenoid; ar, articular; bt, basitemporal; d, dentaryl en, external nostrils, e.o, exoccipital; eth, ethmoid; fr, frontal; j, jugal; lc, lacrymal; mx, maxilla; mx.p, maxillopalatine process; n, nasal, parietal; pg, pterygoid; pl, palatine; ps, presphenoid; px, premaxilla; q, quadrate; q.j, quadratojugal; s.ag, supra-angular; s.o, supraoccipital; sq, squamosal; ty, tympanic cavity; v, vomer; II, foramen for optic nerve; V, for trigeminal." (From Wiedersheim.)" A. H. Evans, 1900

Diagram of the Skull of a Wild Duck

"Skull of a Wild Duck (Anus boscas), from the side. ag, Angular; als, alisphenoid; ar, articular; bt,…

"Ichthyornis victor and I. dispar, ...were small forms of about the size of a Partridge, with the habits and appearance, it is presumed, of Terns or Gulls. The head was extremely large in proportion to the remainder of the skeleton; the beak was long and pointed, with entirely separate rami to the mandible; the sharp teeth, fixed regularly in distinct sockets, were inclined backwards, and occupied the whole of the lower and at least the posterior half of the upper jaw; the keel of the sternum was large and broad; the dorsal and cervico-dorsal vertebrae were biconcave. the quadrate articulated to the skull by one knob,... the metatarsus was short and the whole foot small; a furcula was probably present; the wings were well developed, indicating great powers of flight; while the tail was comparatively short, and ended in a pygostyle." A. H. Evans, 1900

Skeleton Head of a Ichthyornis

"Ichthyornis victor and I. dispar, ...were small forms of about the size of a Partridge, with the habits…

The giant elk ranged from Ireland to the borders of Italy. The Irish Elk or Giant Deer was a species of Megaloceros and one of the largest deer that ever lived. The name "Giant Deer" is preferred as it is not related to either of the living species of elk. The Skeleton of Extinct Giant Elk (Megacerous hibernicus) of Ireland, compared with the skeleton of man.

Extinct Giant Elk

The giant elk ranged from Ireland to the borders of Italy. The Irish Elk or Giant Deer was a species…

In zoology a skeleton is any fairly rigid structure of an animal, irrespective of whether it has joints and irrespective of whether it is biomineralized. The mesohyl functions as an endoskeleton in most sponges, and is the only skeleton in soft sponges that encrust hard surfaces such as rocks. More commonly the mesohyl is stiffened by mineral spicules, by spongin fibers or both. Portion of a wall of sponge (fig 17) showing the outer layer (e), the inner layer (i), consisting of collared cells, and the middle layer (m), consisting of irregular cells.

Skeleton of Sponge

In zoology a skeleton is any fairly rigid structure of an animal, irrespective of whether it has joints…

The marine isopod or sand flea (Caprella) is an omnivorous feeder that eats detritus, one-celled plants, small invertebrates. It is preyed upon by shrimp, sea anemones and several fish species. Females of some species of skeleton shrimp apparently kill the males after mating using a poisonous claw.

Marine Isopod

The marine isopod or sand flea (Caprella) is an omnivorous feeder that eats detritus, one-celled plants,…

"Ichthyornis, though the wings are well developed, with fused metacarpals, and the sternum is keeled, the vertebrae present the extraordinary primitive character of being biconcave." Elliot Coues, 1884. This bird is believed to come from the Cretaceous of North America and is a seabird."

Restoration of Ichthyornis

"Ichthyornis, though the wings are well developed, with fused metacarpals, and the sternum is keeled,…

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the perforate test free and calcareous, its several chambers inflated or globose and arranged in a turbinate spiral, the aperture simple or multiple and conspicuous, opening into an umbilical depression, and no supplementary skeleton or canal system." -Whitney, 1911

Globigerina

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the…

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the perforate test free and calcareous, its several chambers inflated or globose and arranged in a turbinate spiral, the aperture simple or multiple and conspicuous, opening into an umbilical depression, and no supplementary skeleton or canal system." -Whitney, 1911

Globigerina

"Globigerina bulloides. GLOBIGERINIDAE. A family of chiefly pelagic foraminiferous rhizopods, with the…

"Fig 27. - Bones of the right wing of a duck, Clangula islandica, A, shoulder, omos; B, elbow, ancon; C, wrist, carpus; D, end of principal finger; E, end of hand proper, metacarpus. AB, upper arm, brachium; BC, fore-arm, antibrachium; CD, whole hand or pinion, manus; composed of CE, hand proper or metacarpus, excepting d2; ED, or d2, d3, d4, fingers, digits, digiti, h, humerus; rd, radius; ul, ulna; sc, outer carpal, scapholunare or radiale; cu, inner carpal, cuneiforme or ulnare; these two composing wrist or carpus. mc, the compound hand-bone or metcarpus, composed of three metacarpal bones, bearing as many digits - the outer digit seated upon a protuberance at the head of the metacarpal, the other two situated at the end of the bone. d2, the outer or radial digit, commonly called the thumb or pollex, composed or two phalanges; d3, the middle digit, of two phalanges; d4, the inner or ulnar digit, of one phalanx d2 is the seat of the feathers of the bastard wing or alula. D to C (whole pinion), seat of the flight feathers called primaries; C to B (fore-arm), seat of the secondaries; at B and above it in direction of A, seat of tertiaries proper; below A, in direction of B, seat of scapularies (upon pteryla humeralis), often called tertiaries. The wing shown half-spread: complete extension would bring A B C D into a right line; in complete folding C goes to A, and D to B; all these motions nearly in the plane of the paper. The elbow-joint and wrist are such perfect hinges, that, in opening or closing the wing, C cannot sink below the paper, nor D fly up above the paper, as would otherwise be the effect of the pressure of the air upon the flight-feathers. Observe also rd and ul are two rods connecting B and C; the construction of their joining at B and C, and with each other, is such, that they can slide lengthwise a little upon each other. Now when the point C, revolving about B, approaches A in the arc of a circle, rd pushes on sc, while ul pulls back cu; the motion is transmitted to D, and makes this point approach B. conversely, in opening the wing, rd pulls back sc, and ul pushes on cu, making D recede from B. In other words, the angle A B C cannot be increased or diminished without similarly increasing or diminishing the angle B C D; so that no part of the wing can be opened or shut without automatically opening or shutting the rest..." Elliot Coues, 1884

The Bones of the Right Wing of a Duck

"Fig 27. - Bones of the right wing of a duck, Clangula islandica, A, shoulder, omos; B, elbow, ancon;…

"Fig. 28. - Mechanism of elbow-joint. ..., where rc and uc show respectively the size, shape, and position of the radial condyle and ulnar condyle of the humerus. It is evident that in the flexed state of the elbow, as shown in the middle figure, the radius, rd, is do pushed upon that its end projects beyond ul, the ulna; while in the opposite condition of extension, shown in the lower figure, rd is pulled back to a corresponding extent." Elliot Coues, 1884

Mechanism of the Elbow-Joint

"Fig. 28. - Mechanism of elbow-joint. ..., where rc and uc show respectively the size, shape, and position…

"Fig. 29., from a young grouse (Centrocercus urophasianus, six months old), is designed to show the composition of the carpus and metacarpus before the elements of these bones fuse together: r, radius; u, ulna; s, scapholunar or radiale; c, cuneiform or ulnare; om, a carpal bone believed to be os magnum, later fusing with the metacarpus; z, a carpal bone, supposed to be unciform, later fusing with metacarpus; 8, an unidentified fifth carpal bone, which may be called pentosteon, later fusing with the metacarpus; 7, radial or outer metacarpal bone, bearing the pollex or outer digit, consisting of two phalanges, d and k; 9', principal (median) metacarpal bone, bearing the middle finger, consisting of the two phalanges, d', d"; 9, inner or ulnar metacarpal, bearing a digit of one phalanx, d'". The pieces marked om, z, 7, 8, 9,. all fuse with 9'. (From nature by Dr. R. W. Shufeldt, U.S.A.)."Elliot Coues, 1884

The Wing Bones of a Young Grouse

"Fig. 29., from a young grouse (Centrocercus urophasianus, six months old), is designed to show the…

"Fig. 31. - Ulna of Colaptes mexicanus, showing points of attachment of the secondaries. (Dr. R. W. Shufeldt, U. S. A.)." Elliot Coues, 1884

Red Shafted Woodpecker Ulna

"Fig. 31. - Ulna of Colaptes mexicanus, showing points of attachment of the secondaries. (Dr. R. W.…

"Fig. 114. -Skulls of Turdidae and Sylvicolidae, nat. size; after Shufeldt. A, Oroscoptes montanus; B, Sialia mexicana; C, Cinclus mexicanus; D, Siurus naevius. Observe likeness between A and B, at points marked c, c', l, l'; and between C and D, at points marked b, b,' d, d'." Elliot Coues, 1884

Bird Skulls

"Fig. 114. -Skulls of Turdidae and Sylvicolidae, nat. size; after Shufeldt. A, Oroscoptes montanus;…

"Right pectoral arch of a bird. s, scapula; c, coracoid; gl, glenoid, the cavity for head of humerus; cl, clavicle; hc, hypecleidium. In situ, the right end of the figure should tilt up a little. The pectoral arch is that bony structure by which the wings are borne upon the axial skeleton. It is to the fore limb what the pelvic arch is to the hind limb; but is disconnected from the back-bone and united with the breastbone, whereas the reverse arrangement obtains in the pelvic, which is fused with the sacral region of the spine. Each pectoral arch of birds consists (chiefly) of three bones: the scapula and coracoid, forming the shoulder-girdle proper, or scapular arch; and the accessory clavicles, or right and left half of the clavicular arch." Elliot Coues, 1884

The Right Pectoral Arch of a Bird

"Right pectoral arch of a bird. s, scapula; c, coracoid; gl, glenoid, the cavity for head of humerus;…

"Fig 56 - Axial skeleton, minus the skull, of an owl, Asio wilsonianus, life size; from nature by Dr. R.W. Shufeldt, USA. at, atlas; ax,axis; cv, cervical vertebrae; c, c', cervical ribs, or free pleurapophyses; dv, dorsal vertebrae, excepting the last one, which joins the sacrum; R, two of the six true ribs (pleurapophyses), whereof sr is sacral; u, one of the five uncinate processes or epipleura; cr, two of the six sternal ribs(haemapophyses), whereof the sixth floats; p, pelvic or sacral region of the spine, comprehending one dorsal, and several lumbar, sacral proper, and urosacral vertebrae; I ilium; Is, ischium; P pubis; a, acetabulum; in, ischio-iliac foremen; o, obturator foramen; clv, caudal or coccygeal vertebrae, whereof py is the pygostyle; s, scapula; ohs, os humero-scapulare; cl, clavicle; C, coracoid; S, sternum." Elliot Coues, 1884

Axial Skeleton

"Fig 56 - Axial skeleton, minus the skull, of an owl, Asio wilsonianus, life size; from nature by Dr.…

"Pelvis of a heron (ardea herodias), nat. size, viewed from below; from nature by Dr. R.W. Shufeldt, U.S.A. dl, dorso-lumbar vertebrae to and including the last one, sc; below sc, for the extent of the large black spaces (opposite the arrow) are the true sacral vertebrae; us, urosacral vertebrae (opposite the five oval black spaces; Il, ilium; Is, ischium; P, pubis; ob, obturator foramen. The arrow flies into the acetabulum.

The Pelvis of a Heron

"Pelvis of a heron (ardea herodias), nat. size, viewed from below; from nature by Dr. R.W. Shufeldt,…

"Pelvis of a young grouse, showing three distinct bones. Il,P, ilium, ischium, pubis. In front of former a dorsal vertebra protrudes." Elliot Coues, 1884

The Pelvis of a Young Grouse

"Pelvis of a young grouse, showing three distinct bones. Il,P, ilium, ischium, pubis. In front of former…

Megatherium ("Great Beast") was a genus of elephant-sized ground sloths that lived from two million to 8,000 years ago. A related genus was Nothrotheriops, which were primarily bear-sized ground sloths. The rhinoceros-sized Promegatherium is suggested to be the ancestor of Megatherium.

Megatherium Skeleton

Megatherium ("Great Beast") was a genus of elephant-sized ground sloths that lived from two million…

"Fig. 62 Skull of common fowl, enlarged. from nature by Dr. R.W. Shufeldt, U.S.A. The names of bones and some other parts are printed, requiring no explanation; but observe the following points: The distinction of none of the bones composing the brain-case (the upper back expanded part) can be found in a mature skull. The brain is contained between the occipital, sphenoidals, squamosals, parietals and part of frontal; the ethmoidals belong to the same group of cranial bones proper. All other bones, excepting the three otic ear-bones, are bones of the face and jaws. The lower jaw, of five bones, is drawn detached; it articulates by the black surface marked articular with the prominence just above- the quadratic bone. Observe that from this quadrate a series of bones quadrato-jugal, jugal, maxillary-makes a slender rod running to the premaxillary; this is the zygoma, or jugal bar. Observe from the quadrate also another series, composed of pterygoid and palatine bones, to the premaxillary; this is the pterygo-palatine bar; it slides along a median fixed axis of the skull, the rostrum, which bears the loose vomer at its end. The under mandible, quadrate, pterygoid, and vomer are the only movable bones of this skull. But when the quadrate rocks back and forth, as it does by its upper joint, its lower end pulls and pushes upon the upper mandible, by means of the jugal and pterygo-palatine bars, setting the whole scaffolding of the upper jaw in motion. This motion hinges upon the elasticity of the bones of the forehead, at the thin place just where the reference-lines from the words "lacrymal" and "mesethmoid" cross each other. The dark oval space behind the quadrate is the external orifice of the ear; the parts in it to which the three reference-lines go are diagrammatic, not actual representations; thus, the quadrate articulates with a large pro-otic as well as with the squamosal. The great excavation at the middle of the figure, containing the cirlet of the unshaded bones, is the left orbital cavity, orbit, or socket of the eye. The mesethmoid includes most of the background of this cavity, shaded diagonally. The upper one of the two processes of bone extending into it from behind is post-frontal or sphenotic process; the under one (just over the quadrate) is the squamosal process. A bone not shown, the presphenoid, lies just in front of the oval black space over the end of basisphenoid. This black oval is the optic foramen, through which the nerve of sight passes from the brain-cavity to the eye. The black dot a little behind the optic foramen is the orifice of exit of a part of the trifacial nerve. The black mark under the letters "on" of the word "frontal" is the olfactory foramen, where the nerve of smell emerges from the brain-box to go to the nose. The nasal cavity is the black space behind nasal and covered by that bone, and in the oval blank before it. The parts of the beak covered by horn are only premaxillary, nasal, and dentary. The condyle articulates with the first cervical vertebra; just above it, not shown, is the foramen magnum, or great hole through which the spinal medulla, or main nervous cord, passes from the spinal column. The basioccipital is hidden, excepting its condyle; so is much of the basisphenoid. The prolongation forward of the basisphenoid, marked "rostrum," and bearing the vomer at its end, is the parasphenoid, as far as its thickened under border is concerned. Between the fore end of the pterygoid and the basisphenoidal rostrum, is the site of the basipterygoid process, by which the bones concerned articulate by smooth facets; further forward, the palatines ride freely upon the parasphenoidal rostrum. In any passerine bird , the vomer would be thick in front, and forked behind, riding like the palatine upon the rostrum. The palatine seems to run into the maxillary in this view; but it continues on to premaxillary. The maxillo-palatine is an important bone which cannot be seen in the figure because it extends horizontally into the paper from the maxillary about where the reference life "maxillary" goes to that bone. The general line from the condyle to the end of the vomer is the cranial axis, basis cranii, or base of the cranium. This skull is widest across the post-frontal; next most so across the bulge of the jugal bar." Elliot Coues, 1884

Skull of a Common Fowl

"Fig. 62 Skull of common fowl, enlarged. from nature by Dr. R.W. Shufeldt, U.S.A. The names of bones…

This letter W is enclosed in a box with a background design of a human skeleton.

Letter W

This letter W is enclosed in a box with a background design of a human skeleton.

"Ideal plan of the double-ringed body of a vertebrate. N, neural canal; H, haemal canal; the body separating them is the centrum of any vertebra, bearing e, and epapophysis, and y, a hypapophysis; n, n, neurapophyses; d, d, diapophyses; ns, bifid neural spine; pl, pl, pleurapophyses; h, h, haemapophyses; hs, bifid haemal spine. Drawn by Dr. R. W. Shufeldt, USA, After Owen. The Axial Skeleton of a bird or any vertebrated animal, that is, one having a back-bone, exhibits in cross-section two rings or hoops, one above and the other below a central point, like the upper and lower loops of a figure 8. The upper ring is the neural arch, so called because such cylinder encloses a section of the cerebro-spinal axis, or principal nervous system of a vertebrate (brain and spinal cord, whence arise all the nerves of the body, excepting those of the sympathetic nervous system). The lower ring is the haema arch, which similarly contains a section of the principal blood vessals and viscera.

Axial Skeleton

"Ideal plan of the double-ringed body of a vertebrate. N, neural canal; H, haemal canal; the body separating…

"Fig 55. - Actual section of the body in the thoracic region of a bird. N, neural canal; H, haemal canal; c, centrum of a dorsal vertebra; hy, hypapophysis; d, diapophysis; z, zygapophysis; ns, neural spine; r, pleurapophysis, or vertebral part of a free rib, bearing u, uncinate process or epipleura; cr, haemapophyses; or sternal part of the same; st, section of the sternum or breast-bone (haemal spine). Designed by Dr. R. W. Shufeldt, USA. This figure shows such a section, made across the thoracic or chest-region of the trunk. Here the upper ring (neural) is contracted, only surrounding the slender spinal cord, while the lower ring is expanded to enclose the heart and lungs." Elliot Coues, 1884

The Axial Skeleton

"Fig 55. - Actual section of the body in the thoracic region of a bird. N, neural canal; H, haemal canal;…

An illustration of the front left tarsus of a penguin. "a, articular facet for inner condyle of tibia; b, articular facet for outer condyle; c, c, two foramina, showing incomplete fusion of three metatarsals; d, point of attachment of accessory metatarsal; 2, 3, 4, articular facets for second, third, and fourth toes." -Century, 1889

Front Left Tarsus of a Penguin

An illustration of the front left tarsus of a penguin. "a, articular facet for inner condyle of tibia;…

"Phalacrocorax bicristatus. Cormorant. The knee-joint of a Cormorants. F, femur; P, patella; T, tibia; Fb, fibula

The Knee-joint of a Cormorant

"Phalacrocorax bicristatus. Cormorant. The knee-joint of a Cormorants. F, femur; P, patella; T, tibia;…

"Phalacrocorax bicristatus. Red-Faced Cormorant. Sternum and the shoulder from the skeleton of a Cormorant." Elliot Coues, 1884

Cormorant Sternum and Shoulder

"Phalacrocorax bicristatus. Red-Faced Cormorant. Sternum and the shoulder from the skeleton of a Cormorant."…

"Phalacrocorax bicristatus. Red-Faced Cormorant. Skull showing sto, occipital style or nuchal bone; The style is somewhat tilted upward from its natural position." Elliot Coues, 1884

Cormorant Skull

"Phalacrocorax bicristatus. Red-Faced Cormorant. Skull showing sto, occipital style or nuchal bone;…

"F. Fibula; T, tibia, with a, its cnemial process, and P, large patella, of a grebe." Elliot Coues, 1884

Leg Bones of a Grebe

"F. Fibula; T, tibia, with a, its cnemial process, and P, large patella, of a grebe." Elliot Coues,…

"Dromaeognathous skull of a tinamou (Tinamus robustus); copies by Shufeldt from Huxley. Letters as before; Mxp, maxillo-palatine. The tinamous, Dromaeognathae "have a completely struthious palate"; vomer very broad, uniting in front with broad maxillo-palatine plates as in Dromaeus; behind articulating with posterior ends of palatines and anterior ends of pterygoids, both of which are thus prevented, as in all Ratitae, from any extensive connection with the rostrum; basipterygoid processes springing from body of sphenoid, not from its rostrum, articulating with pterygoids very near the posterior or outer ends of the latter; head of quadrate with a single articular facet, as in Ratitae." Elliot Coues, 1884

The Skull of a Tinamou

"Dromaeognathous skull of a tinamou (Tinamus robustus); copies by Shufeldt from Huxley. Letters as before;…

"Desmognathous skull of mallard duck, Anas boscas, nat. size, from nature, by Dr. R.W. Shufeldt, U.S.A. Letters before. In the "bound-palate" type, the vomer in either abortive, or so small that it disappears; when existing it is usually slender and tapers to a point in front; the maxillo-palatines are united across the median line, either directly or by means of ossification in the nasal septum; the posterior ends of the palatines and the anterior ends of the pterygoids articulate directly with the rostrum (as in schizognathism). This type is simply and perfectly exhibited by a duck in which the maxillo-palatine is a broad flat plate united with its fellow in mid-line; the oval sessile basipterygoid facets are far forward, opposite the very ends of the pterygoids." Elliot Coues, 1884

Mallard Duck Skull

"Desmognathous skull of mallard duck, Anas boscas, nat. size, from nature, by Dr. R.W. Shufeldt, U.S.A.…

"Mature stapes of fowl, about x4; after Parker. st, its foot, fitting fenestra ovalis; mst, main shaft, or medio-stapedial element; sst, supra-stapedial; est, extra-stapedial; ist, infra-stapedial, its end representing a rudimentary stylo-hyal; f, a fenestra in the extra-stapedial." Elliot Coues, 1884

The Ear Bone of Fowl

"Mature stapes of fowl, about x4; after Parker. st, its foot, fitting fenestra ovalis; mst, main shaft,…

A collapsible boat includes a skeleton and an impervious skin tensioned about the skeleton. The skeleton includes a plurality of longitudinal and transverse frame members forming stringers and former, the frame members being attached to the gunwale frame of the boat and the transverse members being turn able relative to the gunwale frame. The flexible skin is permanently attached to the gunwale frame and the longitudinal frame members are hinge connected to the gunwale frame at front and rear portions thereof. The longitudinal members are turn able relative to the gunwale frame in a direction transversely of the boat, and the longitudinal frame members along their horizontal portion each being provided with one or more hinge members turn able through an angle of 180&deg;.

Collapsible Boat

A collapsible boat includes a skeleton and an impervious skin tensioned about the skeleton. The skeleton…