Chat with AIExam 1: The Whale and the Virus: How Scientists Study Evolution
Before DNA evidence, scientists had a difficult time discerning where cetaceans fit into the mammalian family tree. Based on morphological features used to classify artiodactyls, why would it have been difficult to link cetaceans to artiodactyls based on morphological evidence alone? How do more recent discoveries in the fossil record link cetaceans to artiodactyls?
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Answered by Examlex AI CopilotBefore DNA evidence, scientists had a difficult time linking cetaceans to artiodactyls based on morphological evidence alone because cetaceans, which include whales, dolphins, and porpoises, have undergone significant adaptations for their aquatic lifestyle. These adaptations, such as their streamlined bodies, flippers, and lack of hind limbs, make it challenging to see the similarities between cetaceans and artiodactyls, which are even-toed, hoofed mammals like deer, pigs, and hippos.
However, more recent discoveries in the fossil record have provided evidence linking cetaceans to artiodactyls. Fossil evidence shows that cetaceans share a common ancestor with artiodactyls, likely a small, deer-like mammal that lived around 50 million years ago. This common ancestor had features of both groups, such as a hoofed foot with an odd number of toes, which is a characteristic of artiodactyls. Additionally, genetic studies have also supported the link between cetaceans and artiodactyls, showing that they share a close evolutionary relationship.
Overall, while morphological evidence alone may have made it difficult to link cetaceans to artiodactyls in the past, recent discoveries in the fossil record and genetic studies have provided strong evidence for their evolutionary connection.
Mammary glands in whales and humans
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VerifiedD
From examining the fossil record, scientists have postulated that long-term historic changes in cetacean diversity depended on
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You discover a new 50-million-year-old fossil that you believe might be an ancient cetacean. The creature looks nothing like a modern cetacean-it has four legs and clearly spent considerable time on land. Describe one feature that would indicate that this creature was, in fact, an early cetacean.
(28) Describe one piece of evidence that indicates that early four-legged whales such as Indohyus and Pakicetus are more closely related to modern-day whales than they are to the closest living four-legged relative of modern whales, the hippopotamus.
(35) Biologist Theodosius Dobzhansky wrote an essay in 1973 entitled "Nothing in ______ Makes Sense Except in the Light of ______."
(46) The influenza virus has only ten genes, which is far fewer than other nonviral organisms. Why do you think viruses are able to survive and replicate with so few genes compared to other organisms?
(34) The placement of whales within the artiodactyls is supported by
(39) Sirenians (manatees and dugongs) are aquatic mammals that, like whales, lack hind limbs. Is lack of hindlimbs a homologous trait for sirenians and cetaceans?
(36) What is a scientific theory, and how does this differ from how we often use the term in a nonscientific context?
(30) Describe how scientists used carbon isotopes to determine whether extinct whales likely inhabited freshwater or saltwater.
(30) The molecular clock used to date the emergence of the 2009 H1N1 strain would be inaccurate if
(23) When scientists infected vaccinated and nonvaccinated mice with influenza, they found that after nine sequences of viral passage the hemagglutinin protein was altered in one of the groups. Which group was it, and what is the evolutionary explanation for the differences between the groups?
(34) Given the phylogeny of extant and extinct cetaceans below, which of the following conclusions is correct? 
(35) In the context of epidemiology, what does it mean to describe the world as "smaller"?
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