Precambrian Eon: Introduction Name______Instructions: Read through the Precambrian Eon introduction. Then complete the “Fill Ins” below. 4.6 Billion Geologists have separated the Earth’s geologic history into Years ago several spans of time called “Eons” and “Eras”. Eons are the Precambrian Eon largest time segments and Eras span shorter blocks of time. The oldest segment is known as the “Precambrian”. The Precambrian Eon began over 4 Billion years ago and represents 88% of the Earth’s geologic time. The more recent “Eras” are known as; Paleozoic, Mesozoic, and our present era the Cenozoic. Because the Precambrian Eon was such a long time ago, little is known about it. Much of what we know has been discovered by scientists in the last 50 years. Some of the oldest fossils from the Precambrian are tiny bacteria found in Australia. These fossils date back over 3.4 billion years old. Some of these ancient fossils are known as “Stromatolites” 540 Million and were a form of Cyanobacteria or “Algae”. They were Years ago common in the shallow seas of the primitive Earth. Paleozoic Era Stromatolites lived in large communities that would build up layers of rock-like microbial mats year after year. Stromatolite fossils have been found all over the world and represent one the most important organisms of the Stramatolite Layers Precambrian Eon. 251 Million Years ago Mesozoic Era Complete the “Fill Ins” using the information above. 1- Largest span of geologic time is referred to as an ______. 2- The ______Eon represents 88% of Earth’s history. 65 Million 3- Some of the oldest fossils are ______billion years old. Years ago Cenozoic Era 4- Common algae is also known as ______. 5- ______lived in large shallow sea communities. 6- The ______era is our present geologic era. Present Day 7- Stromatolites form ______of rock-like mats. 8- Some of the oldest known fossils are found in ______. Paleozoic Era: Introduction Name______Instructions: Read through the Paleozoic Era introduction. Then complete the “True False” statements below. 4.6 Billion The Paleozoic Era represents the geologic time from 251 Years ago to 540 million years ago. The Paleozoic was a time of Precambrian Eon widespread geological, climatic, and biological change. The beginning of the Paleozoic is sometimes referred to as the “Age of Invertebrates” as several new and important animal species began to appear in the oceanic fossil record. One such creature, the Trilobite, Trilobite became the world’s dominant species for the first part of the Paleozoic. Many scientists believe the Trilobite’s hard exoskeleton helped them become so successful. Ancient As the Paleozoic Era continued, more Fish and more species began to appear. Fish, arthropods, amphibians and reptiles all 540 Million Years ago developed during the Paleozoic. Paleozoic Era Many of the species during the Paleozoic Era Primitive developed in the oceans, however eventually Plant transitioned onto land. By the late Paleozoic, the land was dominated by various forms of organisms. Great forests of primitive plants covered the continents and towards the end of the era, large reptiles were dominant and 251 Million some the first modern plants appeared. Years ago Mesozoic Era Although a successful era, the Paleozoic ended 251 million years ago in a mass extinction event that is still debated by scientists today. Select True or False for each statement below. 65 Million Years ago 1- The Paleozoic is the oldest geologic time segment. True - False Cenozoic Era 2- Trilobites were the first land animals. True - False 3- “Age of Invertebrates” refers to early Paleozoic. True - False 4- Fish and horses appeared during the Paleozoic. True - False Present Day 5- Reptiles developed by the end of the Paleozoic. True - False 6- Most Paleozoic animals lived in the sea. True - False 7- The Paleozoic lasted over 400 million years. True - False 8- Modern plants appeared during the Paleozoic. True - False Mesozoic Era: Introduction Name______Instructions: Read through the Mesozoic Era introduction. Then complete the “Fill -Ins” statements below. The Mesozoic Era represents the geologic time from 65 4.6 Billion to 251 million years ago. The Mesozoic is also referred to Years ago Precambrian as the “Age of Reptiles”, and is an exciting era because of Eon the development of dinosaurs. Ancient Although dinosaurs were an important T-Rex Fish development during the Mesozoic, other geologic events occurred. It was during the Mesozoic that the ancient supercontinent of “Pangaea” began to separate due to tectonic forces. Not only were the continents changing during the Mesozoic, but the climate was Pangaea also changing. Periods of warmer and cooler temperatures occurred several times during the era. Another important event was the development of Mammals 540 Million near the end of the Mesozoic. Years ago Paleozoic Era During the middle of the Mesozoic large land dinosaurs were the dominant species. Brachiosaurus, one of the tallest known dinosaurs, and Diplodocus both appeared during this time. Although very large, scientist believe they were both herbivores. Near the end of the Mesozoic, meat eating Tyrannosaurus Rex and a flying dinosaur called a Pterosaur became numerous and successful. The 251 Million Mesozoic Era came to an end 65 million years ago with the Years ago Mesozoic Era extinction of the dinosaurs. Many scientists believe several events, including an asteroid impact near Mexico, led to the dinosaur extinction and the end of the era. Complete the “Fill Ins” using the information above. 65 Million 1- The Mesozoic Era is also known as the ______Reptiles. Years ago Cenozoic Era 2- ______the supercontinent separated during the Mesozoic. 3- Near the end of the Mesozoic, ______developed.

4- One of the tallest known dinosaurs was called ______. Present Day 5- Pterosaur was a special dinosaur that could ______in the sky. 6- The ______era ended about 65 million years ago. 7- ______is one of the most famous meat eating dinosaurs. 8- The Mesozoic Era may have ended due to an ______impact. Cenozoic Era: Introduction Name______Instructions: Read through the Cenozoic Era introduction. Then complete the “True False” statements below. The Cenozoic Era represents the geologic time from 4.6 Billion present day to 65 million years ago. The Cenozoic is also Years ago Precambrian referred to as the “Age of Mammals”. Some of the largest Eon mammals to ever walk the Earth appeared during this era. Ancient Although the Cenozoic represents a smaller section of Fish Earth’s geologic time, more fossils have been found with more details than any other era. With the extinction of the dinosaurs, mammals were able to become the dominant species on the Earth. Many varieties of mammals became successful ranging from small rodent- like mammals to Woolly Mammoths. Mammoth Some of the most famous mammals include Saber- Toothed Tigers, Mastodons, and the largest terrestrial mammal, the “Paraceratherium”, a 16 foot tall rhino that 540 Million roamed the Eurasian plains. Years ago Paleozoic Era Plants also made developments during this era. Modern day flowering plants, grasses and evergreens populated the landscapes around the globe. It was during the Cenozoic that Earth experienced widespread cooling periods known as “Ice Ages”. Several ice age events occurred that influenced mammal development and migration. 251 Million During the last 4 million years of the Cenozoic, Years ago Mesozoic Era the modern “Hominids” or humans appeared in the fossil record. Originating in Africa, these mammals spread across Europe, Asia and beyond.

Select True or False for each statement below. 65 Million Years ago 1- The Cenozoic Era lasted about 65 million years. True - False Cenozoic Era 2- There are very few fossils from the Cenozoic Era. True - False 3- The Cenozoic Era is known as the “Age of Trees”. True - False 4- Large mammals existed during the Cenozoic. True - False Present Day 5- The largest mammal ever was a type of Rhino. True - False 6- Flowering plants appeared during the Cenozoic. True - False 7- Hominids existed during the entire Cenozoic Era. True - False 8 - Several ”Ice Ages” occurred during the Cenozoic. True - False Geologic Time: Timeline Activity Name______Instructions: Use the “Geo-Bank” to complete the timeline by filling in the blanks with the correct events or species. Then color code according to color key. Precambrian Eon Paleozoic Era Mesozoic Era Cenozoic Era

• ______• ______• ______• ______

• ______• ______• ______• ______

• ______• ______• ______• ______

4.6 Billion------540 Million------251 Million------65 Million------Present -”Geo-Bank”- Age of Invertebrates Age of Reptiles Stromatolites Thrive Ice Ages Oldest Time Period Saber-Toothed Tiger Pterosaur Flew Trilobites Dominate Age of Mammals 88% of Earth’s Time Primitive Plants Pangaea Splits

-”Color Key”- Color code each Geologic Time box using the colors below. Precambrian Eon Paleozoic Era Mesozoic Era Cenozoic Era Brown Red Green Blue