Lab 2 Museum of Comparative Zoology

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201

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Anthropology

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Dec 6, 2023

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Birds of the world The beak of each of these five birds is intricately adapted to its specific food source. The Black-necked Stork, with its heavy black beak, efficiently captures fish, small crustaceans, and amphibians. The Wandering Albatross possesses a large, hooked bill that allows it to snatch fish from the water with ease. The Whooping Crane, marked by its long, pointed beak, feeds on a variety of foods such as crustaceans, mollusks, and small fish. The American Flamingo, recognized for its distinct pink coloration, has a specialized beak that enables it to filter-feed on brine shrimp and blue-green algae. Lastly, the Wild Turkey's beak, though relatively small, assists in foraging for seeds, vegetation, and insects, demonstrating the remarkable correlation between a bird's beak and its particular food source.

Wild Turkey Wild turkeys have a diverse diet, being omnivorous, which means they consume a variety of foods, including both plants and animals. Their food choices encompass seeds, vegetation, and insects. The beak of a wild turkey is relatively small, typically measuring between 2 to 3.2 cm in length for adults. They employ this beak to peck at the ground in search of anything that might have been uncovered. Additionally, they occasionally pick fruits or other edibles from plants. American Flamingo Flamingos are water birds found in salt lakes and coastal regions, known for their vibrant pink feathers, which derive their color from carotenoid pigments present in their diet. These birds

employ filter-feeding to consume brine shrimp and blue-green algae. Their bills are uniquely adapted to separate mud and silt from their food, and they use them upside-down for this purpose.

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Whooping Crane The Whooping Crane possesses a lengthy, dark, and pointed beak. Its diet is quite diverse, consisting of crustaceans, mollusks, fish, berries, small reptiles, and aquatic plants. These birds engage in foraging, occasionally using their bills to probe for food.

Wandering Albatross The Wandering Albatross is a nocturnal feeder, and its diet consists of cephalopods, small fish, and crustaceans. It's characterized by a sizable, pink, hooked bill that is specially adapted for catching food. These albatrosses use their hooked bills to dip into the water and seize fish as part of their feeding process.

The Black-necked Stork The Black-necked Stork is characterized by its robust black beak, featuring a slightly curved upper edge. This stork primarily feeds on a diet that includes fish, small crustaceans, and amphibians. To capture its prey, it employs a method of jabbing and seizing with its substantial bill. Questions: How many toes does this specimen have? This specimen has three toes per foot. Do the teeth have cusps or ridges? The teeth have ridges. What do you notice about the positions of the teeth in the upper versus the lower jaw? The teeth are almost identical in shape on both the upper and lower jaws. Nevertheless, the upper jaw teeth exhibit a slight curvature at their tops, whereas the lower jaw teeth remain straight. These teeth also feature a solitary gap located behind the front teeth. What kinds of food do you think this animal ate? The Mesohippus most likely ate twigs and fruit. Think about the modern-day horse, Equus (look at the specimen in the case nearby)—how does the toe number and tooth shape differ in this earlier species (Mesohippus)? What do you think this implies in terms of habitat change or resource change? In contemporary times, horses possess hooves instead of toes. Notably, the teeth of Equus, the modern horse, are larger in comparison to the teeth of Mesohippus. These bodily adaptations exemplify the concept of horses evolving and enhancing their characteristics over time in response to shifts in habitats and available resources. The transition from toes to hooves in horses is attributed to its efficiency, enabling them to achieve greater speed. Furthermore, the shift from

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smaller to larger teeth in horses facilitates the chewing and gnawing of food with greater ease and effectiveness. Examine Parahippus. How many toes does this species have? The Parahippus, the species following the Mesohippus, also had three toes. Which toe(s) is/are walked upon? Parahippus adopted a stance where it primarily relied on its central middle toe for support, enabling it to achieve higher running speeds compared to its ancestors. Ligaments in the central toe played a vital role in reinforcing the horse's body weight. As a result, the side toes had minimal contact with the ground, contributing to the horse's improved speed and agility. Why would such a change in the toes and a change in which toe(s) were stood upon be advantageous? This adaptation was instrumental in enhancing the Parahippus's running speed, with its two additional toes hardly ever making contact with the ground. The feet of the Parahippus represented a transition towards evolving hooves, and as time progressed, the remaining toes eventually disappeared entirely. If it is possible to view the teeth, examine them. How have they changed? It appears that an additional molar tooth is evident in the Parahippus. These teeth exhibited higher crowns and developed a tougher enamel for effectively crushing grass and other leafy plants. What do the changes imply in terms of food resources being used? As leafy vegetation became less common, the Parahippus had to rely on the newly evolved grasses that were increasingly dominating the plains. In response to this dietary shift, their teeth adapted to better suit the consumption of grass. Compare Mesohippus, Parahippus, and Equus. What is happening to the fore- and hindlimbs (humerus-radius-ulna and femur-tibia-fibula)? The evolutionary journey of the horse traces a path from the Mesohippus to the Parahippus and culminates in the modern-day Equus. Over this progression, the horse's hind limbs gradually grew longer, larger, and more robust. The leg bones fused together, and muscles developed, enabling the horse to achieve swiffer forward and lateral movements. As mentioned earlier, the teeth adapted by becoming larger to better handle changing leafy plants. Additionally, the horse's feet transformed from having three toes to a single hoof, a critical development that enhanced its speed and agility. Why do you think these changes are occurring? These changes took place gradually over an extended period to allow the animal to adapt and thrive in response to the changing ecosystem. If the animal had not evolved in sync with the evolving world around it, it would likely have faced extinction. This principle holds true for the majority of species over the course of millions of years. What advantage would they provide?

The alterations in the teeth, feet, and legs of the horse over the span of many years facilitated its growth in terms of size, speed, strength, and overall efficiency. Today's Equus represents a vastly improved and superior horse compared to its Mesohippus ancestor. When does the horse become single-toed? Do you think that modern-day horses could be born with three toes today (i.e., be a “sport of nature”)? Why or why not? The transition to a single toe occurred several million years ago when the Equus, the contemporary horse, became dominant. In a technical sense, horses are born with five toes, a legacy from their ancestors that existed millions of years ago. However, during development, those four additional toes either don't fully develop or disappear. Nevertheless, although incredibly rare, it is conceivable for an individual horse to be born with abnormalities, going beyond the single hoof. Such occurrences can be due to a variety of factors, including unusual birth defects. Besides the limb changes, teeth changes, and toe changes, what else changes during horse evolution? What hypotheses can you form concerning the ultimate reasons for these changes? Earlier horse species were relatively small and primarily browsers of forest vegetation. However, the transition from forests to expanding grasslands due to changing climate conditions prompted a rapid evolution in horses. Apart from the alterations in the size and number of their limbs, teeth, and toes, the horses have also experienced a significant increase in their overall size. Some modern horses are now twice the size of their historical ancestors. Furthermore, their dietary habits have shifted towards the grazing diet that we commonly associate with horses today. Where are the descendants found today? This particular fish is a coelacanth that was captured in 1965 near the Comoro Islands, situated north of Madagascar. These ancient fish are not extinct but incredibly scarce. Currently, we are aware of only two populations from two different species that still exist: the Comoro Coelacanth found off the African coast and the Sulawesi Coelacanth located in Indonesia. Unfortunately, both of these species are considered endangered. Examine the fish specimens mounted on the wall behind the Coelocanth. What do you notice about the tail configuration of the fossil fish from Green River and that of the Coelocanth? Sketch some examples. Coelacanths, along with other lobe-finned fish, possess paired pectoral and pelvic fins that are supported by bones similar to those found in our own arms and legs. The tail of the Coelacanth is distinct in being broader, whereas the tails of the fish mounted on the wall behind it are divided into two sections. Compare the pectoral fin supports for these fish with that for the Coelocanth. How do they differ?

The pectoral fins, positioned on the sides of a fish, play a crucial role in its movement. In the case of the Coelacanth, these pectoral fins are noteworthy for their wide range of motion, resembling the function of oars. They allow the Coelacanth to make precise adjustments in its position, aiding in maintaining its location. The pectoral fins of the other fish are also situated high on the sides, which grants them excellent maneuverability in swimming, much like the Coelacanth's pectoral fins. Early bony fishes had what kind of covering? (look up on the wall) What happens to the scales with later day bony fishes? In early bony fish, it seems they possessed bony and scaly external structures. However, as time has progressed, the scales of fish have become smoother and largely diminished. Modern-day fish typically exhibit bodies that are smooth and covered in a layer of mucus. Find the model of Tiktaalik roseae. How does this fish compare with the Coelocanth ( whats similar what’s different )? Why is Tiktaalik considered a “ missing link “? Coelacanths stand out as a unique group among all living fishes due to their distinct characteristic of possessing an additional lobe on their tails. This distinguishing feature sets them apart from other fish species like Tiktaalik. Thus it's missing a link because of its mix of land and sea animal. Find the 42-foot long skeleton of Kronosaurus, a marine dinosaur in ROMER HALL. How many “fingers” are there in its paddle-like front fin? There are five “fingers” on the Kronosaurus’ front fin.

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What is the primitive (most ancient) phalangeal formula for reptiles? (HINT: look at some of the other reptile skeletons in the room and note that our phalangeal formula is 2-3-3-3-3 or 2 for the thumb and 3 for all other fingers.) The primitive phalangeal formula for reptiles is 2-3-4-4-5. What is the formula for Kronosaurus? Just by guessing while looking at the phalangeal of the Kronosaurus, it seems to have an approximate formula of 8-10-10-9-8. What has happened to the phalangeal formula? (This is known as “hyperphalangy”. Over time, certain species have exhibited a phenomenon known as "hyperphalangy," which refers to an increase in the number of bones within the phalangeal formula. What would be the advantage of the condition of hyperphalangy? Hyperphalangy enables fish to move at faster speeds than one might anticipate, thanks to their elongated fins. These larger fins provide them with increased surface area, allowing them to generate more power and achieve greater speed. A fish that is larger and faster is likely to have a higher chance of survival compared to a slower fish. Do you see evidence of hyperphalangy in other reptiles in the room? If so, list them. Yes, the cetacean seems to have a case of hyperphalangy. Can you find other examples of hyperphalangy in the museum? (Hint: check the Great Mammal Room) What are they? It seems that the Giant Whale skeleton has a case of hyperphalangy. How do you think that hyperphalangy arises? (HINT: remember back to the comparison with the number of thoracic vertebrate in a chick versus a snake and how that was caused.) Hyperphalangy is a result of malformations in the body, particularly due to a lack of cell death between the fingers and toes. Where are the external nares located on Kronosaurus? The external nares are located on the Kronosaurus’ nose in the back of its head. Compare this position to where the nostrils are located on other reptiles? Why do you think they are located in this position? In most reptiles, the nostrils are situated at the front of their noses. This arrangement likely evolved because it's more advantageous for an animal's sense of smell to be closely aligned with the area it's investigating. Placing the nostrils at the back of the head would be impractical in this context. Do you see this alteration in position of external nares in any other group elsewhere in the museum? (Hint: check the Great Mammal Room) Specify. The Great Whale, housed in the Great Mammal Room, underwent a significant evolutionary change over time as its nose gradually shifted further back on its skull.

Are these similarities between phytosaurs (Kronosaurus) and the other group due to recent common ancestry or to similar ecologies? What is the evidence for your answer? The Kronosaurus and the whale share a similar pattern of evolution. This is likely because both animals evolved in the same or similar habitats, necessitating them to adapt to their environments in a similar manner, resulting in a comparable shift in nasal structure. “ Arthropods : Creatures that Rule “ The Rockefeller Bettles group includes numerous species that differ in different ways, including length, size, head shape, patterns, and color intensity in specific body parts. Individual variation within a species can be explained by a mix of genetic, environmental, and evolutionary variables. These changes can be caused by genetic variety, mutations, and genetic drift. Environmental factors such as diet, habitat, and climate may also contribute to these disparities. Furthermore, natural selection might cause particular characteristics to become more prominent or adapted over time.There are various advantages to having variation within a species. For starters, it enables a species to adapt to a variety of settings and changing conditions. It acts as a genetic reservoir, ensuring that some individuals of the population are more likely to survive and reproduce when faced with new problems. This genetic diversity can be critical to the long-term survival of a species. Furthermore, polymorphisms can be important for sexual selection because they increase the attractiveness of potential mates, enhancing reproductive success. Overall, the presence of variation in a species is beneficial since it increases the species' resilience, enables adaptability to varied settings, and aids the process of evolution and natural selection, ultimately contributing to the species' survival and success. The Glass Flowers exhibit there wasn't any rotten apples available Looking back on my experience with this assignment, I must admit it turned out to be quite a pleasant surprise. Initially, I had my doubts about working on an out-of-school task, but my visit to the Harvard Museum of Natural History proved to be both educational and enjoyable. As I approached the museum's red-brick building, I couldn't help but be impressed by the sense of history that surrounds Harvard University. The campus exudes an unmistakable aura of academic importance, and it had me captivated before I even set foot inside. As my friends and I explored the museum, our interactions mainly consisted of light-hearted banter and cheerful exchanges. Furthermore, while I moved through the museum's intricate exhibits, I often found myself pausing to read the detailed descriptions on the walls. Surprisingly, I'm on the path towards marketing, a field that is completely different from the world of science. Nonetheless, I indeed found myself fascinated with certain scientific aspects, particularly prehistoric creatures. Out of all the exhibits in the museum, I found the "Birds of the World" gallery to be the most captivating. Perhaps it's because I encounter various bird species in my daily life, sparking my curiosity and prompting me to learn more about them. Or it's because they are simply so colorful

and fascinating. Nevertheless, the museum as a whole offered a rewarding and intellectually stimulating experience. I truly enjoyed this assignment and was captivated by everything the museum had to offer.

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Lab 2 Museum of Comparative Zoology

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