Crocodiles have existed for over 200 million years and survived the mass extinction that wiped out the dinosaurs 65 million years ago. They were well-adapted to both land and water environments and able to survive periods without food due to their cold-blooded metabolism and slow growth rate. Modern crocodiles face threats from habitat loss and illegal killing but there are 13 species that still inhabit tropical regions of Asia, Africa and the Americas as apex predators in aquatic ecosystems.

1. Crocodiles
Bryan Galvan
GEL 103
Lake Tahoe Community College

2. History: Pre-Historic Age
Crocodiles are one of a few species which
lived and flourished among the
dinosaurs
Their prehistoric ancestors were far more
diverse in how and where they lived
Some would walk around like dogs on
land, while others lived in the open
ocean.
Ancient crocodiles represent a diverse
ecology

3. History: Evolution Timeline
Xilousuchus(250,000,000 bc - 200,000,000 bc)
● 3 Feet long
● 5-10 LB
● Split off into Pre-Historic crocodiles and
dinosaurs
Phytosaur(228,000,000 bc - 199,000,000 bc)
● Alive during early Jurassic Period.
● Were herbivores
● Looked like modern day crocs.
Erpetosuchus(200,000,000 bc)
● Did not resemble modern day
crocodiles
● Bipedal
Sarcosuchus (110,000,000 bc)
● Middle Cretaceous Period
● 40 feet long (10-15 Tons)
● Ate dinosours and fish
● Lived in the rivers of Africa
Stomatosuchus(100,000,000 bc - 95,000,000 bc)
● Very big (about 36 feet long)
● Ate mostly krill and plankton, even though
they had a peleca like mouth.

4. History: Evolution Timeline
Beinosuchus(80,000,000 bc)
● Beinosuchus (Greek word
for terrible crocodile)
● 33 feet long (10 tons)
● Lived in North American
Rivers
● Attacked large species
Champsosaurus(70,000,000 bc - 50,000,000 bc)
● 5 feet long (25-50 LBS)
● Ate fish
● Lived on North America and Europe
Cretaceous-Paleogene Extinction Event
(65,000,000 bc)
● This extinction was very intense in whipping out
Flora, Fauna, and Dinosaurs
● Strangely, the crocodiles managed to survuve.
Crocodylidae (Modern day crocodile)
55,000,000 bc - Present
● The modern day crocodile. Although it
may look prehistoric, it is far from it.
● Highly evolved and complex predator
● Includes Salt water, Nile, and American
crocs.

5. How Did Crocodiles Survive Mass Extinction?
65 million years ago, during the Cretaceous period, there was a huge meteorite
which struck the planet.
The meteorite impact resulted in worldwide climate changes
Due to climate changes, there was extinction known as the K-T Extinction
(Cretaceous–Tertiary Extinction)

6. Theories of Survival
Theory #1: Crocodiles were well adapted
Have pretty much stuck with the same body for the
past 200 million years
Theory #2: Crocodiles inhabited water areas
Crocodiles lived halfway between land and large
patches of fresh water
Surprisingly, the meteor had less of an impact on
fresh and salt waters.

7. Theories of Survival
Theory #3: They are cold blooded
Crocodiles possess the “reptilian” cold-blood
Slower metabolism, which allows them to go without food for
longer
Cold blood allows them to survive in dark and cold places
Theory #4: Crocodiles grow at a slower pace
Crocodiles grow at a slow and steady pace throughout their
lives

8. Theories of Survival
Theory #5: Crocodiles were more intelligent than dinosaurs
Very controversial hypothesis
Scientists believe that crocodiles are as smart as cats and
dogs
However, there were other animals that were just as
smart (or even smarter) than the crocodile, yet, they
still managed to go extinct.
Today, there are animals that still go extinct. Yet, the
crocodile manages to survive and still thrive.

9. Modern Day Crocodiles
Species: 13
Family: Crocodylidae
Class: Reptilia
Kingdom: Animalia
Phylum: Chordata
Order: Crocodylia
Genera: Crocodylus, Mecistops and Osteolaemus
Crocodiles are found in the tropical areas of Asia, Africa,
and the America.
There are 13 types of species for crocodiles, so there size
could vary.
Carnivorous (only eat meat)

10. Modern Day Crocodiles
Mostly live in freshwater habitats
Feed on mammals and fish
Live in tropical areas for a reason.
Cannot generate their own heat, so they
rely on the warm habitat in which
they live in
Life span depends on their species
Can live from 30 to 75 years

11. Threats
At one point in their history, the
crocodiles were hunted down for
their hides.
Loss of habitat due to human
occupation
Illegal killing and roadkill
Due to climate change, a large
portion of the crocodile's habitat
(wetlands) may face saltwater
invasion

12. References:
Choi, C. Q. (2013, September 10). How Crocs Survived in Dinosaur-Dominated World. Retrieved June 25, 2017,from
https://www.livescience.com/39551-how-crocs-survived-dinosaur-dominated-world.html
Bradford, A. (2014, June 25). Crocodiles: Facts & Pictures. Retrieved June 25, 2017, from
https://www.livescience.com/28306-crocodiles.html
BENTON, M. J. (2011). MASS EXTINCTIONS. New Scientist, 209(2802), i-viii.
University of Bristol. (2013, September 10). Jurassic jaws: How ancient crocodiles flourished during the age of the
dinosaurs. ScienceDaily. Retrieved June 25, 2017 from www.sciencedaily.com/releases/2013/09/130910205505.htm
University of Edinburgh. (2014, October 15). Prehistoric crocodiles' evolution mirrored in living species. ScienceDaily.
Retrieved June 25, 2017 from www.sciencedaily.com/releases/2014/10/141015101725.htm