Millions of years ago, ancestors of modern crocodiles lurked in the shallow waters of lakes and other bodies of water. They hunted fish and other animals, much as their descendants do today. If you could travel back in time to visit one of those lakes, you might see the ancestors of today’s hippos there as well. Antelopes might browse along the edges of the lake, and rodents of various sizes might scurry back and forth. When paleontologists examine the fossil of a prehistoric organism, they may discover clues about the organism’s life. They may also answer questions about the environment it lived in: Was the area hot or cold? Was it humid or dry? Then, by putting all of these clues together, the paleonologists may be able to learn a little more about how organisms and environments change over time. Unfortunately, studying a fossil site is no easy task! Often, a paleontologist may find a few teeth scattered over a very large area. In such cases, keeping track of where the fossils were found is very important.
In this activity, you will use the data from a fossil site to create a map of fossil locations at that site. Then you will make some conclusions about the past environment, or paleoenvironment, at that location. The table below shows the locations of fossils that were found spread out over 22,500 m2. A team of paleontologists decided that this site, which measured 150 m x 150 m, was too large to work on all at once. Therefore, they decided to create a grid of 10 m squares. Starting in the northwest corner, they labeled the squares with the letters A-O from west to east. Then the team numbered the squares 1-15 from north to south. In this way, each fossil could be labeled with a letter and a number, depending on where it was found. For instance, the label A1 would signify the 10 m x 10 m square in the northwest corner of the site. Similarly, the label O15 would indicate the square in the southeast corner of the site.
1. What do you already know about hippos?
5. What makes an idea scientifically valid?
Location of Fossils
B11,C6,D3, I15,J10,L7, M6
A5,A6,E2, E4,E14,H7, H8,H12,K4, M1,N15
* Bovids are antelopes and other similar animals
Create a map of the fossil site. The scale should be 1 cm = 10 m. Label the grid of squares with letters and numbers.
Using letters, show where the fossils were found. (Put an Hin each square where a hippo tooth was found; use Rto indicate a rodent tooth, use Cto show a crocodile tooth, and Bfor a bovid tooth.
Use a different color for each layer of sediment, and make a key to show which colors are which. (Example: Layer A - red, Layer B - blue, Layer C - green)
Based on the distribution of fossils in level B, what part of this site might have been covered by water? Devise a way to indicate that part on you map. (Example: Lightly shade with a color)
Questions: Directions: Answer the following questions in complete sentences.
Explain why you chose to shade part of your map as once covered in water.
Describe how the environment at this site changed through time.
Where your answers to question 1 & 2 observations or inferences? Explain.
What can make scientist’s conclusions about past environments more valid?
One member of the team wished to look for fossils of dry-climate plants at this site. Which layer or layers do you think would be most likely to yield fossils of this kind? Explain your answer.
When the paleontologists were analyzing these data, they proposed several hypotheses to explain the changing climate. One of them suggested that tectonic uplift had occurred, causing the area to gain elevation over time. A second paleontologist disagreed, stating that the area probably lost elevation over time. Whom do you agree with? Explain your answer in detail.
Sum up how can scientists make valid conclusions about past environments?
Rodentia is an order of mammals also known as rodents, characterised by two continuously-growing incisors in the upper and lower jaws which must be kept short by gnawing.
Common rodents include mice, rats, squirrels, chipmunks, gophers, porcupines, beavers, hamsters, gerbils, guinea pigs, degus, chinchillas, and groundhogs. Rodents have sharp incisors that they use to gnaw wood, break into food, and bite predators. Most eat seeds or plants, though some have more varied diets. Some species have historically been pests, eating human seed stores and spreading disease.
bovid is any of almost 140 species of cloven-hoofed mammals belonging to the family Bovidae. The family is widespread, being native to all continents except South America, Australia and Antarctica, and diverse: members include buffalo, bison, antelopes, gazelles, both wild and domesticated cattle, sheep, goats, and water buffalo.
The largest bovid, the Gaur, weighs well over a ton and stand 2 metres high at the shoulder; the smallest, the Royal Antelope, weighs about 3 kg and stand no taller than a large domestic cat. Some are thick-set and muscular, others lightly built with small frames and long legs. Many species congregate into large groups with complex social structures, but others are mostly solitary. Within their extensive range, they occupy a wide variety of habitat types, from desert to tundra and from thick tropical forest to high mountains.
Most members of the family are herbivorous, except most duikers, which are omnivorous. All bovids have a four-chambered stomach which allows most of them to digest foods that are too low in nutriment for many other animals, notably grasses. No higher animal directly digests cellulose, but like kangaroos, termites and others, bovids rely on micro-organisms living in their stomachs to break down cellulose by fermentation.
Because of the size and weight of their complex digestive systems, many bovids have a solid, stocky build; the more gracile species tend to have more selective diets, and be browsers rather than grazers. Their upper canine teeth and incisors are missing, and are replaced with a hard, horny pad, that the lower teeth grind against to cut grass or other foliage. The canines are either missing or modified to act as extra incisors. The cheek teeth are low-crowned and selenodont, and are separated from the forward teeth by a wide gap, or diastema.  The dental formula for bovids is similar to that of other ruminants:
The hippopotamus (Hippopotamus amphibius), from the Greek ἱπποπόταμος (hippopotamos, ιππος hippos meaning "horse" and πόταμος potamus meaning "river"), often shortened to "hippo", is a large, mostly plant-eating African mammal, one of only two extant species in the family Hippopotamidae (the other being the Pygmy Hippopotamus).
The hippopotamus is semi-aquatic, inhabiting rivers and lakes in sub-Saharan Africa in groups of 5-30 hippos. During the day they remain cool by staying in the water or mud; reproduction and childbirth both occur in water, where territorial bulls preside over a stretch of river. They emerge at dusk to graze on grass. While hippos rest near each other in territories in the water, grazing is a solitary activity and hippos are not territorial on land.
Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoise, etc.). The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago.
The hippopotamus is recognizable for its barrel-shaped torso, enormous mouth and teeth, hairless body, stubby legs and tremendous size. It is similar in size to the White Rhinoceros; only elephants are consistently heavier. Despite its stocky shape and short legs, it can easily outrun a human. Hippos have been clocked at 30 mph (48 km/h) while running short distances, faster than an Olympic sprinter. The hippopotamus is one of the most aggressive animals in the world. There are an estimated 125,000 to 150,000 hippos remaining throughout Sub-Saharan Africa, of which Zambia (40,000) and Tanzania (20,000-30,000) have the largest populations . They are still threatened by poaching for their meat and ivory canine teeth, and by habitat loss.
A crocodile is any species belonging to the family Crocodylidae (sometimes classified instead as the subfamily Crocodylinae). The term can also be used more loosely to include all members of the order Crocodilia: i.e. the true crocodiles, the alligators and caimans (family Alligatoridae) and the gharials (family Gavialidae), or even the Crocodylomorpha which includes prehistoric crocodile relatives and ancestors. Crocodiles are large aquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodiles tend to congregate in freshwater habitats like rivers, lakes, wetlands and sometimes in brackish water. They feed mostly on vertebrates like fish, reptiles, and mammals, sometimes on invertebrates like mollusks and crustaceans, depending on species. They are an ancient lineage, and are believed to have changed little since the time of the dinosaurs. They are believed to be 200 million years old whereas dinosaurs became extinct 65 million years ago; crocodiles survived great extinction events.[1