Bone types

Top: Metacarpals (long bones) and carpals (short bones) Second row, left: Left ulna (long bone) Second row, right: Scapula and sternum (flat bones) Third row, left: Sagittal section of the knee joint, including the patella (sesamoid bone) Third row, right: Thoracic vertebrae (irregular bones) Bottom: Complete Skeleton

Bones are classified into five groups, organized by shape.

Long bones are longer than they are wide, and are subjected to most of the load-bearing responsibilities in everyday life. These include the humerus, radius, and ulna (arms); fibula, femur, and tibia (legs), as well as the phalanges (fingers and toes), metacarpals (hands) and metatarsals (feet).

They grow from the epiphysis (growth plate) at either end of the bone, and failure of these bones to grow causes the majority of dwarfism cases.

Short bones are as wide as they are long, and provide support, but do not bear heavy loads or move much. These include the tarsals (feet) and carpals (hands/wrists).

Flat bones are broad bones that provide protection to organs, and large areas for muscle attachment. These include the bones in the skull, the ilium, scapula, sternum, and ribs. The flat bones consist of two layers of compact bone, surrounding a layer of cancellous bone, where the majority of red bone marrow exists. In adults, most red blood cells are produced in the flat bones.

Sesamoid bones are bones within tendons, which pass over a joint. The most familiar sesamoid bone is the patella, or knee-bone. These bones provide protection to delicate joints.

Irregular bones don't fit into any of the above categories. The mandible and vertebrae are irregular bones.

Images:

Atlas and Text-book of Human Anatomy. Dr. Johannes Sobotta, 1914. Anatomy: Descriptive and Applied. Henry Gray, 1918. A Series of Engravings, representing the Bones of the Human Skeleton. William Cheselden, 1819.

Natural history terminology: Lazarus Taxon

Lazarus taxon is originally a paleontology term, referring to the disappearance in the fossil record (generally indicating extinction or a very small number of individuals) of a species that emerges again in a much later era. The term is also used in neontology (the study of extant creatures) when referring to a species believed to have gone extinct that is later found to still exist.

In the Book of John, Jesus raises the man named Lazarus, and brings him back to life more than four days after his death. Hence the term "Lazarus taxon" is quite applicable - the species was believed extinct, but was "brought back" in the records as it were, when it was re-discovered after the date of its being declared extinct.

A counterpart to the Lazarus taxa (singular of taxon) is the Elvis taxa. This term is used when a species assumed extinct from the fossil record is incorrectly thought to have re-emerged at a later date, but is found to be a like-looking species that adapted a form similar to the original species, thanks to convergent evolution. The original species did not re-appear, but the impostor species was so similar that the original was believed to have re-appeared when the impostor was first discovered.

This term comes from, well, "Elvis" sightings, and Elvis impersonators. Clearly they're not Elvis, but some look similar enough at first that they could fool professionals who had no way to confirm that Elvis was dead. The fossil record is so spotty that a disappearance of a species doesn't always indicate an extinction, and paleontologists are used to many species re-appearing in later eras (it's less common in neontology), so the first instinct is to classify the discovery as a re-emergence.

I like how that platypus over on the left side seen as being just as related to birds and reptiles as they are to mammals. Those buggers messed up our organization of animals for quite a while.

Actually, in 1833,  a lot of naturalists still didn't believe that the platypus was, well, "real". They thought the specimens that had been brought back and stuffed were hoaxes! There was a report of an 1840s Paris Zoological Society meeting where one of the stuffed specimens was brought in, and some of the members were trying to find where the beak and venomous spine and webbed feet were connected. They nearly destroyed it!

Dictionnaire Pittoresque d’Histoire Naturelle et des Phenomenes de la Nature. F. E. Guerin, 1833.

Dictionnaire Pittoresque d’Histoire Naturelle et des Phenomenes de la Nature. F. E. Guerin, 1833.

Dictionnaire Pittoresque d’Histoire Naturelle et des Phenomenes de la Nature. F. E. Guerin, 1833.

Triaxeopus cornutus

This octopus' species is currently under debate. It was known as Octopus cornutus (Owen) for a while, and was considered to be in the "Octopus horridus" group. Horrible octopus. Horrible horrible octopus.

Transactions of the Zoological Society of London, Volume XI. 1885.