| Question Answer | The most common Precambrian fossils are ________, layered mounds of calcium carbonate. stromatolites | The ________ era is known as the “age of flowering plants.” Cenozoic | ________ are among the most widespread Paleozoic fossils Brachiopods |
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What are the most common Precambrian fossils?
Common Precambrian fossils include
mats of algae called stromatolites
, microorganisms, and simple animals.
What is the name of the most common Precambrian fossils which are layered mounds of calcium carbonate?
The most common Precambrian fossils are
stromatolites
. Stromatolites are distinctively layered mounds or columns of calcium carbonate.
What animal group became the dominant land animals of the Cenozoic Era?
Mammals
replaced reptiles as the dominant land animals in the Cenozoic era.
Which represents the greatest expanse of geological time?
Eons
represent the greatest expanses of time.
How old is the oldest fossil on Earth?
The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated
3.5 billion years old
. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old!
Why are there no fossils from the Precambrian era?
Fossils are rare in Precambrian rocks mostly
because Precambrian life-forms lacked bones, or other hard parts that commonly form fossils
. One of the few Precambrian fossils that have been discovered are stromatolites.
Which organism produces oxygen first?
And some evidence suggests
cyanobacteria
, the earliest photosynthetic organisms to release oxygen gas as a waste product—although not use it—may have arisen as early as 3.5 billion years ago.
What era is known as the age of flowering plants?
The Cenozoic Era
, from 65 million years ago to today, is the age of mammals and flowering plants and is marked by global cooling.
Which two characteristics best separate humans from other mammals?
What two characteristics best separate humans from other mammals?
Upright posture and bipedalism
.
Why isn't there an end for the Cenozoic Era?
There were a few extinctions over this period due
to the changing climate
but plants adapted to the various climates that emerged after the glaciers retreated. Tropical areas never had glaciers, so lush, warm-weather plants thrived all during the Quaternary Period.
What era do we live in?
We live in the
Holocene Epoch
, of the Quaternary Period, in the Cenozoic Era (of the Phanerozoic Eon).
What are some interesting facts about the Cenozoic Era?
Cave lions, sabre-toothed cats, cave bears, giant deer, woolly rhinoceroses, and woolly mammoths were prevailing species of the Quaternary period. Without the dinosaurs,
plant life
had an opportunity to flourish during the Cenozoic era. Nearly every plant living today had its roots in the Cenozoic era.
Which is the second greatest expanse of time?
Eon, Long span of geologic time. In formal usage,
eons
are the longest portions of geologic time (eras are the second-longest). Three eons are recognized: the Phanerozoic Eon (dating from the present back to the beginning of the Cambrian Period), the Proterozoic Eon, and the Archean Eon.
Which accounts for the greatest amount of time in Earth's history?
The largest units of time are
eons
; the 4.6 billion years of earth's history are divided into four eons. The Phanerozoic Eon includes the most recent 545 million years and the most detailed fossil record.
What is the shortest period of time in the geologic time scale?
Epochs
.
Epochs
are then divided into ages, which are the shortest division of geologic time.
