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A primary difference between ammonites and nautiloids is the siphuncle of ammonites (excepting Clymeniina) runs along the ventral periphery of the septa and camerae (i.e., the inner surface of the outer axis of the shell), while the siphuncle of nautiloids runs more or less through the center of the septa and camerae.
Goniatite shells are small to medium in size, almost always less than 15 centimeters (5.9 inches) in diameter and often smaller than 5 centimeters (2.0 inches) in diameter. The shell is always planispirally coiled, unlike those of Mesozoic ammonites in which some are trochoidal and even aberrant (called heteromorphs).
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
A decomposing human body in the earth will eventually release approximately 32 g (1.1 oz) of nitrogen, 10 g (0.35 oz) of phosphorus, 4 g (0.14 oz) of potassium, and 1 g (0.035 oz) of magnesium for every kilogram of dry body mass, making changes in the chemistry of the soil around it that may persist for years. [8]
A cross-section of a Nautilus pompilius shell, showing the large body chamber, shrinking camerae, concave septa, and septal necks (partial siphuncle supports) All nautiloids have a large external shell, divided into a narrowing chambered region (the phragmocone) and a broad, open body chamber occupied by the animal in life. The outer wall of ...
On 2021, Stephen Quake guessed that the upper limit of the number of human cell types would be around 6000, based on a reasoning that "if biologists had discovered only 5% of cell types in the human body, then the upper limit of cell types to discover is somewhere around 6000 (i.e., 300/0.05)." [10] Other different efforts have used different ...
The term "ammonite" may indeed be ambiguous. Perhaps Ammonite should be a disambiguation page, although explaining the difference between, say, Ammonoidea, Ammonitida, and Ammonitina would take at least a paragraph. Cheers, Cephal-odd 03:43, 31 May 2010 (UTC)
It is also a portmanteau term that describes all biological aspects of the human body, typically using the human body as a type organism for Mammalia, and in that context it is the basis for many undergraduate University degrees and modules. [4] [5] Most aspects of human biology are identical or very similar to general mammalian biology.