Four levels of geological Time scale in descending order?
- Eons-> Largest intervals; hundreds of millions of yrs
- Eras-> Very significant events in earth’s history are used to demarcate boundaries of eras; tens to Hundreds of million years
- Period-> upto a hundred million yrs
- Epoch-> epochs are chunks of time that describe evolutionary ups and downs of mammals and birds. NOT all periods are divided into Epochs as earlier periods’ rocks are modified to such an extent that they aren’t identifiable.
Eons?
- > Two: Pre cambrian and Phanerozoic
- > Pre-Cambrian is basically a super-eon; extends from the origin of the earth (4.5 Bn yrs ago) to the appearance of first multi-cellular organisms (0.6Bya); ions included within it are Hadean, Archean and Proterozoic
- > Thereafter starts Phnaerozoic eon, that continues upto the present
eras?
- > Pre-cambrian eon: no subdivision
- > Phanerozoic eon: 3 eras
1. Palaeozoic era: frm appearance of first multi-cellular organisms (540Mya) to appearance of first Dinosaurs, mammals, birds (250mya)
2. Mesozoic era: frm appearance of first dinosaurs , mammals, birds (250mya) to extinction of dinosaurs (65mya)
3. cenozoic: extinction of dinosaurs (65mya) to present
Periods of palaeozoic era?
- Cambrian: Cambrian explosion;First chordates; first fish; gondwana emerges
- ordovician: major diversification of invertebrates; First green plants and Fungi appear on land
- Silurian: First vascular plants; Caledonian orogeny begins in UK and Scandinavian mts
- Devonian: First amphibians; first seed bearing plants; first trees and first insects; Acadian orogeny of Applachian and atlas mts
- carboniferous: Large primitive trees; first land vertebrates; amphibians common and diverse; Uralian orogeny
- Permian: Permian-Triassic extinction wipesout 95% of life; reptiles diversify; Landmasses unite into Pangea
Cambrian period?
540-485mya Cambrian explosion first chordates first Fish emergence of Gondwana
(Call for Cancer GF EXPerience- Cambrian, Chordates, Explosion, Gondwana, Fish)
Ordovician period?
485-445 mya
Diversification of invertebrates
First green plant and fungi on land
(Old GIF- Ordovician, Green plants, Invertebrates, Fungi)
Silurian period?
445-420 mya
vascular plants
caledonian orogeny in UK and Scandinavia
(Snake VC- Silurian, Vascular, Caledonian)
Devonian period?
420-360 mya
first amphibians first trees first insects first seed bearing plants Arcadian orogeny- Appalachian and Atlas Mts.
(AmSTIAc- Amphibians, Seed bearing plants, Trees, Insects, Arcadian orogeny)
Carboniferous period?
360-300 mya
first vertebrates on land
Amphibians diversify
Ural orogeny
Large primitive trees
(VAUT- Vertebrates, Amphibians, Ural, Trees)
Permian period?
300-250 mya
Permian-triassic extinction
Reptiles diversify
Landmasses unite to form Pangea
(PREx- Pangea, Reptiles, Extinction)
Periods of Mesozoic era?
- Triassic:First mammals and first dinosaurs; Andean orogeny;Climmerian orogeny in central asia
- Jurassic: First birds; dinosaurs diversify; Breakup of Pangaea into Gondwana and Laurasia.
- cretaceous: extinction of dinosaurs;first primates; flowering plants; Monotremes, marsupials and placental mammals appear;
Triassic period?
250-200 mya
first mammals
first dinosaurs
Andean Orogeny
Climmerian orogeny in Central Asia
(Tv (Triassic)- Monkey (Mammal), Dog(Dinosaurs) and Cheetah (Climmerian) looking at an Anda (Andean))
Jurassic Period?
200-145 mya
First birds
Breakup of Pangea into Gondwana and Laurasia
Diversification of Dinosaurs
(on a Jug (Jurassic)- a Bat (Birds) and a Dog (dinosaurs) chasing a Parrot (Pangea))
Cretaceous period?
145-65 mya
extinction of dinosaurs first primates flowering plants emergence of Monotremes, marsupials and placental mammals atm CO2 similar to present day levels
(Eight (Extinction) Pair (Primates) of Feet (Flowering plants) Made (Monotremes) of Pink (Placental) Marbles (Marsupials) were Cast (CO2))
Periods of Cenozoic era?
- Tertiary: upto beginning of human evolution (1.8mya); most significant period in India’s geological history coz Himalayas were born and India’s present form came into being in this period; called ‘Age of mammals’
- Quarternary: ongoing; evolution of humans
Epochs of Tertiary period?
- Palaeocene:K-Pg extinction event (extinction of non-Avian dinosaurs); First large mammals; Alpine orogeny begins
- eocene: Two transient events of global warming (PETM and ETM-2); Azolla event decreased CO2 levels leading to a long period of cooling; Indian Subcontinent collides with Asia and starts Himalayan Orogeny
- Oligocene: Start of widespread Antarctic glaciation; Rapid evolution and diversification of fauna, especially mammals.
- Miocene: Modern mammal and bird families become recognizable; Grasses become ubiquitous; Ancestor of apes, including humans.
- Pliocene: Australopithecus common in East Africa.
Paleocene Epoch?
65-55 mya
K-Pg extinction event (extinction of non-Avian dinosaurs);
First large mammals;
Alpine orogeny begins
(Pink (Paleocene) Elephants (Extinction), Monkey (mammal) and Ass (Alpine))
Eocene epoch?
55-35 mya
Two transient events of global warming (PETM and ETM-2);
Azolla event decreased CO2 levels leading to a long period of cooling;
Indian Subcontinent collides with Asia and starts Himalayan Orogeny
(Eight (Eocene) Hippopotamus (Himalayan) eating Parrots (PETM) and Ass (Azolla))
Oligocene Epoch?
35-25 mya
Start of widespread Antarctic glaciation;
Rapid evolution and diversification of fauna, especially mammals.
(Old (Oligocene)- Dog (Diversification) and ANT (Antarctic))
Miocene Epoch?
25-5 mya
Modern mammal and bird families become recognizable;
Grasses become ubiquitous;
Ancestor of apes, including humans.
(Mute (Miocene) Frog (Families) (how will he call for mating), Giraffe (Grass) (He is stuck in tree branches bt can’t call for help) and Ass (Ancestor) (He is seeing his brother being eaten by Hippopotamus but can’t cry for help))
Pliocene Epoch?
5-1.8 mya
Australopithecus common in East Africa.
Epochs of Quarternary period?
- Pleistocene: Rise of Homo sapiens.
2. Holocene: 12000 ya; Current interglacial begins ; neolithic agri
Ages in Holocene epoch?
- Greenlandian
- Northgrippian
- Meghalayan
