Earth 103 Final

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Headgear (often elaborate anatomical extensions) was common in ornithiscian dinosaurs. Functional explanations for ornithiscian headgear include which one(s) of the following? -To act as a rudder when swimming or flying -Mate competition--Thickened regions of skulls may have been used to butt heads like mountain goats -Elaborate chambers and passages through the headgear determined the sound of trumpeting vocalizations -Elaborate chambers and passages through the headgear determined the sound of trumpeting vocalizations

-Mate competition--Thickened regions of skulls may have been used to butt heads like mountain goats some scientists thing that thickened skulls in some marginocephalians were used as battering rams to headbutt eachother during mating competitions. -Elaborate chambers and passages through the headgear determined the sound of trumpeting vocalizations some scientists thing that thickened skulls in some marginocephalians were used as battering rams to headbutt eachother during mating competitions. -Elaborate chambers and passages through the headgear determined the sound of trumpeting vocalizations

Georges Cuvier concluded that there had been species alive in the past that no longer existed. Believe it or not, this was a controversial claim at the time. Fossils that didn't look like anything now living were probably mostly just considered something magical, mystical, or abiotic. Meanwhile, things that looked like something living were assumed to either just be those living species (or variants of them) or close relatives that just lived somewhere else (most people didn't travel very far in their entire lifetime anyway). Cuvier, however, was convinced that species extinction was a real occurrence because of all the following observations EXCEPT TWO--which TWO of the following did NOT play a role in Cuvier arguing that fossils represent extinct organisms: -As a skilled anatomist, he could tell that some fossil animals (such as mastodons) were in fact very different than known living animals (like elephants) -Some fossil species that were not known from living populations were big terrestrial animals that would be hard to just miss completely (zoologists were at the time starting to get a good handle on biodiversity... at least of the bigger animals) -There were fossil species that would have been too big to fit on Noah's ark -Stories of a big ape-like creature wandering the wilderness of western North America were clearly made up to scare kids

-There were fossil species that would have been too big to fit on Noah's ark how fossils related to the biblical Flood and to Noah's Ark was really a discussion topic for 19th century naturalists, many of whom were clergy and Christian religious scholars. But, you are correct--Cuvier did not argue that they were too big to fit on the ark... rather he argued that they were too big to be currently 'hiding' in the wilderness. -Stories of a big ape-like creature wandering the wilderness of western North America were clearly made up to scare kids Although it is likely 100% true that stories of Bigfoot and other cryptozoological 'species' are ultimately made up, it's not one of the arguments that Cuvier used to argue for extinction.

In addition to the features that identify dinosaurs as members of the group Archosauria, there are diagnostic characteristics that unite dinosaurs into a single group. Which TWO of the following are diagnostic features of dinosaurs? -scaly skin -a hole in the pelvis -a crest on the tibia -a large body

-a hole in the pelvis Dinosaurs have a hole in the pelvis where the leg attaches--a perforate acetabulum. Dinosaurs also have a crest on their tibia that provides an attachment point for leg musculature. It's called the cnemial crest. -a crest on the tibia Dinosaurs have a crest on their tibia that provides an attachment point for leg musculature. It's called the cnemial crest. Dinosaurs also have a hole in the pelvis where the leg attaches--a perforate acetabulum.

Select all of the following groups that have their roots in the Mesozoic: -trilobites -dinosaurs -mammals -flowering plants

-dinosaurs Dinosaurs are still living today (at least one beaked and feathered group), but they got their start in the early Mesozoic, after which (by the mid-Mesozoic) they evolved an enormous variety of species ranging in size from small birds to the largest land animals ever to have walked Earth. -mammals Although they lived in large part "in the shadows" during much of the Mesozoic, the first mammals show up around the same time as the first dinosaurs. After the Mesozoic (in the Cenozoic), mammals become the most conspicuous large terrestrial vertebrates. -flowering plants not to be overlooked when talking about the fossils that many people find more charismatic (animals, of course), plant evolution has some really interesting things going on in the Mesozoic. The biggest event is the appearance and later diversification of angiosperms ("flowering plants") that now make up the bulk of plant biodiversity.

Which of the following are true about mammoths and mastodons: -mammoths and mastodons are both true elephants -mammoths and mastodons are mammals that lived in the mesozoic -mammoths and mastodons are both probiscideans (the group containing elephants and their relatives--all probiscideans have an elaborate proboscis, or 'nose') -although mastodons appear to have completely disappeared at the end of the ice age (about 10,000 years ago), mammoths survived in some remote locations until about 4,000 years ago

-mammoths and mastodons are both probiscideans (the group containing elephants and their relatives--all probiscideans have an elaborate proboscis, or 'nose') Of the two, only mammoths are actually "elephants." Mastodons diverged from the ancestral lineage of elephants about 25 million years ago, some 15 million years or so before true elephants first evolve. However, both belong to the group Proboscidea, animals with trunks (and for the most part tusks and huge bodies). -although mastodons appear to have completely disappeared at the end of the ice age (about 10,000 years ago), mammoths survived in some remote locations until about 4,000 years ago It's unlikely that we will find mastodons that lived in the Holocene, but within the last 20 years, scientists discovered that there were hold-out populations of mammoths living on Wrangel Island (off the northeast coast of Siberia) that lived well into the Holocene (the last 10,000 years when human civilizations took hold).

which of the following DID NOT occur as a result of the k-pg extinction? -Bird diversified, filling many new ecological roles -Mammals evolved to fill ecospaces made vacant by the extinctions of dinosaurs and other large land animals -ALL dinosaur groups went extinct -Mammals got bigger

ALL dinosaur groups went extinct

which of the following is NOT true of the great oxygenation event? -It was driven by the success of photosynthesizing forms of life that created the oxygen and then kept it at high levels in the atmosphere -It refers to a dramatic increase in atmospheric oxygen about 2.2 billion years ago -It paved the way for the complex multicellular life forms that provide the basis for all currently living plants and animals -It proved beneficial for all life

Although we tend to think of oxygen as being universally good for life, that is based on our perspective looking at current life on Earth. In fact, oxygen was probably toxic to most life forms that we know existed before the G.O.E. The event likely resulted in a major extinction event (albeit one that we can't really directly observe through fossils because fossils are so rare before about 550 million years ago).

What does a LAG represent?

An annual growth line in a long bone LAGs are "Lines of Arrested Growth" that form due to metabolic changes during life that are typically associated with seasonal perturbations in dietary resources. In fossils they are interpreted as delineating annual increments of growth and can be used to calculate growth rates of dinosaurs.

Which of the following statements about endothermy is FALSE? -Endothermic animals have high metabolisms compared to ectothermic animals -Endothermy refers to an animals ability to maintain a constant body temperature -Endothermic animals can't go as long without eating as ectothermic animals can -The geographic ranges of endothermic animals is less constrained than it is for ectothermic animals

Endothermy refers to an animals ability to maintain a constant body temperature Endothermy refers to the capacity for producing sufficient heat internally to keep an animals body "homeothermic" (at a constant body temperature), but it doesn't refer to the ability to maintain a constant body temperature. In fact, it's possible to be homeothermic without being endothermic.

which of the following IS a line of evidence supporting the meteor hypothesis as the primary cause of the k-pg extinction? -The extinction of dinosaur species was a long, drawn out process rather than an abrupt one -There are abundant dinosaur remains from the end of the Cretaceous that show a mass-death of animals simultaneously around the globe -Higher than average iridium concentrations in the clay layer separting Cretaceous and Paleogene rocks -Massive volcanism that produced the Deccan Traps occurred millions of years after the extinction

Higher than average iridium concentrations in the clay layer separating cretaceous and paleogene rocks

Bones of large dinosaurs are necessarily shaped differently than bones of small dinosaurs. This reflects a phenomenon we call allometry. It occurs because

Linear, areal, and volumetric dimensions all scale differently Because volume (mass) increases faster than linear dimensions, an animal twice as tall weighs 8 times as much. The shape of bone that can support the weight of a small animal won't support the weight of a larger animal.

which is NOT true about the geological timeline? -The Triassic is the first Period of the Mesozoic Era -The entire Phanerozoic is very short in comparison to the time before the Cambrian -The Mesozoic is the longest Era in the Phanerozoic -The Paleozoic is the first Era of the Phanerozoic Eon

The Mesozoic is the longest Era in the Phanerozoic

The main reason we use the "elongated thumb" as an identifying feature of Saurischia instead of just the forward-oriented pubis is:

The forward-oriented pubis is simply the "primitive" (ancestral) trait and therefore not a novel trait for Saurischia Both characters are useful for identifying saurischians, but as a 'primitive' trait, the forward-oriented pubis is shared with primitive ("stem") ornithischians as well. The elongated thumb is a feature that evolved within the saurischian lineage.

which of the following occurred as a result of the end-Triassic extinction? -Pelycosaurs went extinct -Pterosaurs went extinct -The morphospace occupied by crurotarsans (ancestral crocodilians) dramatically decreased while the morphospace taken up by dinosaurs increased -Dinosaur diversity declined singificantly, enabling mammals to thrive

The morphospace occupied by crurotarsans (ancestral crocodilians) dramatically decreased while the morphospace taken up by dinosaurs increased

Which of the following lines of evidence suggests (but doesn't prove) that dinosaurs were ectothermic? -The nasal structure of dinosaurs -Predator/Prey ratios of dinosaurs -Dinosaur adaptations that provided insulation -The geographic ranges of dinosaurs

The nasal structure of dinosaurs

which of the following scenarios might produce a stratigraphic sequence that appears to violate Steno's principle of superposition? -A meteorite collision created a dust cloud that then settled over the entirety of Earth's surface creating a new (youngest) layer from dust produced from older rocks -Sediments being deposited on a sloping surface with wind-blown dunes form into sedimentary layers that are angled and 'wavy' -Through tectonic activity, a region of the crust has become completely flipped over making younger layers appear "below" older layers -Erosion destroys a series of sedimentary layers, causing that part of the sedimentary record to be lost forever. Now there is a 'gap' in the record.

Through tectonic activity, a region of the crust has become completely flipped over making younger layers appear "below" older layers The only one of these options that makes sense as a scenario that would appear to violate the principle of superposition is if a portion of the crust had been overturned due to tectonic activity such that upper layers are older than lower ones. This actually does happen in mountain building events, usually through 'crustal folding,' but it is (in most cases at least) easily recognizable by geologists and is not the source of any known anomalies in the stratigraphic record.

various groups of ornithiscians had a feature called a dental battery? what is a dental battery?

a series of closely packed teeth that act together as a single unit to grind or slice food dental batteries were present in hadrosaurs and ceratopsians. They provided a continuous chewing surface made up of many small teeth that worked in concert as if they were actually a single large tooth. Dental batteries grew throughout life with new teeth constantly replacing the old ones as the chewing surface of the battery wore down.

which of the following scenarios is most likely to lead to remains (or other materials) entering the fossil record? -a mineralized shell of a crab falls to the seafloor near a convergent plate boundary -a mountain goat dies in its sleep while resting on a ledge on a high elevation cliff face -a tooth drops into a pond and sinks into the much -a worm dies on the sidewalk

a tooth drops into a pond and sinks into the muck the tooth is mineralized material, the pond setting ensures that it will be buried rapidly and stay that way

what feature convinced Richard Owen that dinosaurs had a more erect posture than other large reptiles (eg alligators and crocodiles)?

a well developed sacrum with firm attachment to the pelvis Owen recognized the sacrum as being very different than that of modern reptiles who have a more sprawling posture

which of the following is a marine invertebrate that went extinct following the k-pg boundary? -plesiosaurs -trilobites -giant squid -ammonites

ammonites

which of the following is NOT evidence of a close relationship between dinosaurs and birds? -Birds and dinosaurs both have/had highly pneumatized skeletons and air sacs throughout their bodies -Birds and dinosaurs both have heterodont dentition -Birds and dinosaurs both have/had feathers -Birds and dinosaurs both make/made nests and protected/incubated their eggs

birds and dinosaurs both gave herterodont dentition

t or f: Crocodiles have changed little over the past 200 million years. In fact, we think the original archosaurs were something very similar to modern crocodiles. That means that birds evolved from something very similar to a crocodile.

false Although it's true that crocodiles look very similar to some of their prehistoric ancestors, we actually think the original archosaur was something very different from a crocodile. In fact even the early crocodylians (things like Postosuchus) were bipedal, terrestrial, and active... in many ways more like dinosaurs. The four-chambered heart in crocodiles is evidence that even their ectothermy (cold-bloodedness) may have been a secondary adaptation... and that the earliest archosaurs were actually endothermic like birds!

t or f: the reason that paleontology is a relatively new science is that ancient peoples never came across fossils because they are all buried (that's how they preserve after all) and were only discovered after humans started mining extensively during the industrial revolution

false Although it's true that paleontology as an established science is relatively new, this isn't because people weren't aware of fossils previously. Even ancient peoples must have come across fossils eroding out of the surface (yes, they necessarily start as buried remains, but areas of deposition can change into areas of erosion due to sea level changes and tectonic activity). However, they lacked a concept for deep time that is required to understand fossils in context as long extinct vestiges of past life. So, they developed legends and myths to explain the fossils they saw. Mining operations during the industrial revolution (as well as various other factors) accelerated the discovery of fossils, but they did not lead to the first discoveries by humans.

t or f: Marie Curie accidentally discovered radioactivity when she was exposing uranium salts to X-ray radiation in order to study it's phosphorescent ("glow-in-the-dark") properties. Uranium kept in a dark drawer was producing it's own radiation--a new source previously unknown. We now call this radiactivity

false Everything about this statement is true EXCEPT the person involved. Although Marie Curie is credited for describing (and naming) radioactivity, this story actually refers to experiences by Henri Becquerel. Marie Curie's contributions can reasonably be considered even more substantial. Becquerel simply accidentally stumbled upon a new observation (often the start of the scientific method). Curie applied scientific methods to understand what the heck was going on.

t or f: The earliest dinosaurs were most like sauropods in their overall body shape and locomotory style.

false The earliest dinosaurs were fairly small, bipedal, and carnivorous. Much like theropods... but very different than sauropods.

t or f: reasons that pelycosaurs such as Dimetrodon are often thought to be dinosaurs (by people who haven't taken this course ;) include that they look like dinosaurs and lived alongside dinosaurs at the same time and in the same environments

false The stratigraphic range (the time span that they lived) for pelycosaurs is the Permian, which is the final period of the Paleozoic. Thus, pelycosaurs, such as Dimetrodon and Edaphosaurus lived long before the first dinosaurs evolved in the Triassic (the first period of the Mesozoic). So, although they may look superficially like dinosaurs (in some ways), pelycosaurs did NOT live alongside dinosaurs.

t or f: The fact that birds and mammals are both warm blooded tells us that they are more closely related to each other than either one is to lizards.

false We don't talk in this class about where lizards fit in the evolutionary family tree of tetrapods, but warm-bloodedness in birds and mammals evolved separately, in each lineage after they split from their common ancestor. So, we treat warm-bloodedness in this case as an analog (rather than a homolog) in birds and mammals.

t or f: faunal succession refers specifically to the increased complexity of life through time. Older rocks contain less complex fossils than younger rocks

false While it's true that faunal succession refers to changes in fossils present in the rock record as you move through time, this change is not necessarily characterized by an increase in complexity. Faunal succession only requires that biodiversity changes over time and that we can thus determine where we are in the "Geologic Column" by looking at the particular assemblage of fossils contained in a stratigraphic layer or series of layers.

t or f: natural selection can explain the variation developed in domestic pigeons, but it rarely explains biological evolution in nature. In fact, most evolution is due to genetic drift, which is random sampling error of alleles in a parent population and is most pronounced when populations are large

false the statement includes multiple false claims. 1) Artificial selection explains the variations produced by breeding domestic pigeons. 2) Although natural selection doesn't explain all evolution, it is commonly involved in the process of developing evolutionary adaptations. 3) The effects of genetic drift are most pronounced in small populations.

which of the following is evidence that birds evolved flight capacities from the "trees down" rather than the "ground up"? -Fossils such as Microraptor suggest an intermediate 'gliding' stage as bird flight evolved -Fossil nests clearly show that the first birds lived high in the trees -Fossils such as Deinonychus suggest that the ancestor of birds was big -The earliest proto-birds had beaks like a woodpecker for capturing insects from under the bark

fossils such as microraptor suggest an intermediate 'gliding' stage as bird flight evolved

Nicolas Steno is considered the "father of modern stratigraphy." One of the contributions he made to paleontology was:

he developed a mechanistic explanation for how solid things like fossil shells and bones could become encased inside rock Nicholas Steno developed mechanistic explanations for how sedimentary rocks formed. He also hypothesized a mechanistic explanation for how fossils got inside rocks--this insight enabled him to think beyond the common explanations of his day for stones people called "tongue stones" or glossopetrae. Rather than tongues of serpents that had been turned to stone by St. Paul, they were actually ancient shark teeth.

which of the following is NOT true about the K-Pg(aka end-cretaceous or K-T) extinction? -It is associated with a known impact event that left a large crater that was discovered in 1992 -It affected various groups in the oceans but only caused dinosaur extinctions on land -It occurred about 66 million years ago -It eliminated all dinosaurs except a few lineages of birds

it affected various groups in the oceans but only caused dinosaur extinctions on land

archaeoteryx was a remarkable discovery because:

it combined an unprecedented assortment of bird- and reptile-like features

deinonychus played an important role in the "Dinosaur Renaissance" that started in the 1960s because:

it showed that at lease some dinosaurs were fast, active hunters

in order of discovery/description, the first three dinosaurs to be recognized by science are:

megalosaurus, iguanadon, hylaeosaurus Megalosaurus was discovered in 1676 and then officially described by William Buckland in 1824; Iguanadon was first discovered in 1822 (possibly by Mary Ann Mantell) and then described by Gideon Mantell in 1825 on the basis of teeth that resembled those of an iguana; Hylaeosaurus was discovered by miners in 1832 and described shortly after by Gideon Mantell in 1833. It was on the basis of these species that Richard Owen created the name Dinosauria to describe this newly discovered group of animals.

List the organisms in order of how closely related they are to birds(closest relative first, most distant relative last): crocodiles, humans, ornithiscian dinosaurs, pterosaurs, trilobites

ornithiscian dinosaurs, pterosaurs, crocodiles, humans, trilobites

These two "accidental" discoveries set the stage for major advances in our understanding of Earth history:

seafloor spreading and radioactivity Both the discovery of seafloor spreading and radioactivity were "accidental." In both cases, scientists were looking for something very different than what ended up being the more important discovery. Both discoveries played major roles in developing our current understanding of Earth's dynamic history.

Fill in the blanks--In an evolutionary story very similar to that of whales, ichthyosaurs evolved from land-living tetrapods. Discovery of fossil evidence _______________________ indicates that they were fully aquatic not needing to return to land, and body forms similar to dolphins and other cetaceans (whale relatives) is an example of ________________________.

that females gave birth to live young tail first; convergent evolution Giving birth to live young meant they didn't have to return to land to lay eggs (think of sea turtles) and the tail-first delivery strongly suggests they were giving birth at sea rather than on shore. The similarity between ichthyosaur and cetacean body plans is a classic examples of what we call convergent evolution. It is where two different lineages independently evolve traits that converge on the same adaptation. In these cases, the similarity is NOT due to shared ancestry, but instead is due to similar lifestyles. In fact, both cetaceans (whales) and ichthyosaurs evolved from different ancestral groups that both lacked aquatic adaptations such as flippers, tail flukes, and dorsal fins.

Place the events in their proper order (according to our current understanding): evolution of the Ediacaran biota, formation of the moon, Great Oxygenation Event, LUCA

the formation of the moon, LUCA, the Great Oxygenation Event, evolution of the Ediacaran biota

all of the following are diagnostic features of Archosauria EXCEPT: -the synapsid skull anatomy -sigmoidal femur antorbital fenestra -thecodont dentition

the synapsid skull anatomy the synapsid skull condition (a single hole or "window" in the skull that the jaw muscle passes through) is different than the diapsid skull condition (two holes for the jaw musculature). Archosaurs are diapsids, but so are many other reptiles... so even the diapsid skull condition is NOT diagnostic of archosaurs. However, three of the diagnostic features I want you to know for archosaurs are the sigmoidal (s-shaped) femur, thecodont teeth (teeth with deep sockets), and the antorbital (in front of the orbit/eye) fenestra. Remember that not all archosaurs have all these features--but those that don't (e.g., birds don't have teeth, so they can't have thecodont teeth) have evolved "away" from the "ancestral" condition.

which of the following is NOT one of the factors that contributed to paleontology's maturation to a widely "respected" scientific field in the second half of the 20th century? -Radiometric dating methods that enable us to put fossils into their proper chronological context -Paleontologist GG Simpson being one of the architects of the "modern synthesis" in biology that merged Darwinian evolution with Mendelian genetics -The advent of computers and the creation of the computational capacity needed to process large datasets in increasingly complex ways -the widespread acceptance by scientist that the vast majority of species that ever existed on Earth are now extinct

the widespread acceptance by scientist that the vast majority of species that ever existed on Earth are now extinct although it is TRUE that the vast majority of species that ever lived are now extinct, this was not one of the factors that contributed to the "paleobiological revolution" that resulted in paleontology being acknowledged as a discipline that can make direct and unique contributions to our understanding of biology and evolution--things that can only be revealed through studying the history of life. The rest of the options are all things that played major roles in the transition of paleontology from the "high chair" to the "high table."

Which of the following (choose one) explains why a series of "nested" relationships provides the best model for categorizing organisms? -Genetic drift can result in evolution without natural selection -Analogous structures can't evolve without close relationships -V.I.S.T cannot result in directional evolution -There are features shared by all living organisms, but closely related species share more genetic features than distantly related species

there are features shared by all living organisms, but closely related species share more genetic features than distantly related species A series of nested relationships provides the best model for explaining the pattern of trait variation we see in biological organisms. All organisms share a few very basic traits. We can create groupings of organisms that share more traits within each group than any group members share with organisms outside the group. Subgroups within subgroups within subgroups can be identified that include ever more closely related species. This pattern is analogous to relationships in a family tree.

Which of the following did we talk about in class as a feature that unites theropods (ceratosaurs, spinosaurs, and coelurosaurs)?

three large digits on each hand All of the characters listed here are characters of at least some theropods, but the only one that unites theropods (is shared by all of the three groups--ceratosaurs, spinosaurs, and coelurosaurs) is three large digits on each hand.

the five major extinction events during the phanerozoic are:

times when the fossil record shows extinction rates significantly higher than the background extinction rate

a pile of trees interpreted as a prehistoric beaver lodge would be considered this kind of fossil that provides direct evidence of the actual behavior and activity of prehistoric organisms

trace fossil trace fossils are created by an organisms activity. in contrast to body fossils, which preserve actual anatomical materials, trace fossils include footprints and other trackways, burrows, gastroliths, gnaw marks, and coprolites (fossilized poo), among other things. The study of trace fossils is called ichnology

t or f: study of magnetic anomalies on the seafloor showed a "mirror-image" in patterns of magnetic reversals preserved in the oceanic crust on either side of the mid-Atlantic ridge. This led scientists to hypothesize that new crust was forming at the ridge and spreading in either direction from it. Marie Tharp is a UM alum who studied this phenomenon and helped develop the hypothesis of sea-floor spreading as a mechanism for Wegener's hypothesis of continental drift

true

t or f: although the wings themselves are considered analogous structures in bats and pterosaurs, individual bones in the wings of each group (such as humerus, radius, and ulna) are homologies due to shared ancestry

true Bats and pterosaurs both have wings composed of homologous bones (e.g., humerus, carpals, phalanges), but the wing structures themselves, even though both are composed of skin stretched from finger bones to the legs, are analogous structures that evolved independently in a process called evolutionary convergence. Each group evolved wings independently from animals without wings. Although the wings look similar in many ways, they have a different underlying structure that reveals different evolutionary histories for each. Convergent evolution can result in similar (analogous) structures when selective pressures push evolution in a particular direction.

t or f: Sauropod necks and backs were made up of complex vertebrae with air-filled pockets that made the vertebrae strong and relatively lightweight.

true The vertebrae of sauropods were highly pneumatized with air-filled pockets between strut-like ridges in the bone that made them both strong and lightweight. The air-filled pockets may also have played a role in their respiratory system.

t or f: the functional significance of ornighopods having a jaw joint offset from the axis of the jaw (a plane extending across the chewing surface of the teeth) is that it made their teeth come together (front and back) all at about the same time. This made their jaws more like adjustable pliers than like scissors

true adjustable pliers have an offset axis of rotation, while the axis of rotation in scissors is inline with the cutting surface. The back part of scissors comes into contact before the tip of the scissors, but in adjustable pliers, the entire gripping surface meets at the same time. This provided ornithopods with an effective chewing apparatus and they are thought to have used their teeth to extensively process their food prior to swallowing (much like cows do... and humans for that matter).

t or f: triceratops was a "bird-hipped" dinosaur, while birds are "lizard-hipped" dinosaurs.

true this is one of the ironic consequences of naming things based on shape before the evolutionary relationships are well understood. Before scientists understood that birds belong to the group Saurischia (lizard-hipped dinos), they noticed that some dinosaurs had a backward facing pubis (like a bird) while others had a forward projecting pubis (like a lizard) and named the groups accordingly. It wasn't until later that we realized birds are actually "lizard-hipped" dinosaurs!


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