Brachiopod : Brachiopoda
Brachiopods (Brachiopoda) are one of the major animal phyla. They are sessile, two-shelled, marine animals that somewhat resemble pelecypod mollusks (i.e. "clams") externally but are quite different internally. Unlike bivalves, which have a left shell and a right shell, brachiopods are always bilaterally symmetric, although the top and bottom shells usually differ in shape. The shells may be either phosphatic or calcaerous. Some fossil forms had elaborate spines.Brachiopods come in two varieties. Inarticulate brachiopods are held together entirely by musculature whereas articulate brachiopods have hinges. Brachiopods are always marine and are found either attached to hard substrates by a structure called a pedicle or resting on muddy bottoms. Brachiopods are filter feeders with a distinctive feeding organ called a lophophore, found among the various different groups of lophophorates.
The earliest known brachiopods are found in the late Neoproterozoic. The first brachiopods were inarticulate, but articulate brachiopods appeared soon thereafter, in the Lower Cambrian. Brachiopods are extremely common fossils throughout the Paleozoic. They were largely replaced by mollusks in the Mesozoic. Brachiopods -- both articulate and inarticulate -- are still present in modern oceans.
The inarticulate brachiopod genus Lingula has the distinction of being the oldest more or less unchanged animal known. The oldest Lingula occur in the very early Cambrian and are roughly 550 million years old. The origin of brachiopods is unknown. A possible ancestor is a sort of ancient "armored slug" called a halkeriid[?] that has recently been found to have had small brachiopod-like shields on its head and tail.
"I see.html">see; I see . . . Can you remember it?"
"Yes . . . I remember it. . . ."
Then the old man.html">man.html">man.html">man.html">man leaned to one side and gazed at the other
are the Philistines?"
"These also. . . ."
"Have all these died out?"
"Yes . . . all. . . ."
"And so . . . we also will die.html">die out?"
"There will come a time when we also will die,"
Scythians and Slavs. . . .
The old man became all the more frightened, and glanced at his face.
"You are lying!" he said scornfully, when the teacher.html">teacher.html">teacher.html">teacher.html">teacher had finished.
"What lie have I told?" asked the teacher.
"You mentioned tribes that are not mentioned in the Bible."
He got up and walked away, angry and deeply insulted.
"You will go mad, Tyapa," called the teacher after him with conviction.
Then the old man came back again, and stretching out his hand.html">hand,
that all people are descended from Jews . . . and we also. . . ."
"Well?"
"Tartars are descended from Ishmael, but he also came of the Jews. . . ."
"What do you want to tell.html">tell me all this for?"
"Nothing! Only why do you tell lies?" Then he walked away,
again and sat by him.
"You are learned . . . Tell me, then, whose descendants are we?
his answer, wishing to understand him.
"Speak to me from the Bible. There are no such men there."
Then the teacher began criticizing the Bible. The old man listened,
there are no Russians? We are not known to God? Is it so?
destroyed them by sword and fire, He destroyed their cities;
the Jews and the Tartars . . . But what about us?
the old man. But the latter put his hand on the teacher's shoulder,
.
On
wordlookup.net
All is still licensed under the GNU FDL.
It uses material from the wikipedia.
|
|