Q: You said you added five percent to the midterm scores because of the class average being lower than last year (70). Will you update the scores on the my UCLA grades anytime soon, because they are still the same without the curve, or just wait and incorporate the new scores into our final grades? And finally, will you be curving the final as well if the average is below last years?
A: I'm not actually going to add 5 percent to the midterm scores, nor to any scores. Instead the distribution of grades will be such that the average score will be approximately a B- (whatever percentage that is). Please see the distribution in the syllabus to get an idea of how the spread of grades will look. Since the average for that distribution was 75% you can approximate what grade you got for each midterm by adding 5% to your own midterm score and see where that falls on the distribution.
Saturday, June 7, 2008
Friday, June 6, 2008
Why is a maniraptor also a tetanuran?
Q: I had a question regarding the cladograms. I think I am still confused on the way to read them. I don't understand #45 on Exam 2. I thought the answer was "maniraptor" but the answer is all of the above. Can you explain this to me in more depth so I understand why that picture represents all of those.
A: Yes, the question was:
The above dinosaur is a:
a. maniraptor
b. coelurosaur
c. tetanuran
d. all of the above
An analogous question might be:
Your pet kitten is a:
a. cat
b. mammal
c. animal
d. all of the above.
all cats are also mammals = all maniraptors are also coelurosaurs.
not all mammals are cats = not all coelurosaurs are maniraptors.
Some mammals are dogs = some coelurosaurs are tyrannosaurs.
You should go through the introductory slides on cladograms and make sure you understand all this. If you are still not sure, you MUST come and see me or your TA! :) We can help explain it.
A: Yes, the question was:
The above dinosaur is a:
a. maniraptor
b. coelurosaur
c. tetanuran
d. all of the above
An analogous question might be:
Your pet kitten is a:
a. cat
b. mammal
c. animal
d. all of the above.
all cats are also mammals = all maniraptors are also coelurosaurs.
not all mammals are cats = not all coelurosaurs are maniraptors.
Some mammals are dogs = some coelurosaurs are tyrannosaurs.
You should go through the introductory slides on cladograms and make sure you understand all this. If you are still not sure, you MUST come and see me or your TA! :) We can help explain it.
Wednesday, June 4, 2008
Identifying flight feathers
Q: I can't really figure out the difference between a flight feather and a body feather - I know that a flight feather has asymmetric vanes but it looks like
body feathers are asymmetrical as well.
A: Do you remember seeing these feathers in the flight lab? One was clearly much more asymmetrical than the other. I suggest you look at the 4th picture down on this page (http://www.earthlife.net/birds/feathers.html) which shows a flight feather(labeled remige) next to a body feather (labeled retrice). The body feather may be slightly asymmetrical, but in most cases there is no doubt about the flight feather's asymmetry.
Is cauditpteryx an oviraptor
Q: I was wondering whether caudipteryx was an oviraptor or an early branch of the coelurosaurs. On slide 66 in lecture 17, caudipteryx is drawn in before tyrannosaurids but in lecture notes 17, it says that caudipteryx is an oviraptor, which would put it in the dromosaur branch right?
A: Good catch! Yes caudipteryx even moves around the tree within that one lecture! Theropod phylogeny is highly debated and as new evidence emerges there are often changes. For caudipteryx there are two levels of confusion. It was originally proposed to be part of a sister group to the birds, but was later widely recognized to be an oviraptor. Oviraptors themselves were thought to be ornithomimids but are now placed within the maniraptor clade. My apologies for not having that updated in the birds lecture. Although, I would not test on this of course and it does give you a taste of the ephemeral reality of some parts of the tree.
Q: on the note about caudipteryx, I was wondering if you could further clarify something for me - I was studying by looking at the cladogram for feather evolution and so am now wondering whether caudipteryx is still seen as an example of stage 2-4 evolution of feathers. If they're placed in the maniraptor clade, then does that mean that the stage 2-4 evolution of feathers came after the ornithomimid clade and so around the same time as the evolution of stage 5 feathers?
A: Another great question! The phylogeny (branching order) within the maniraptors is unclear but I think there are a few reasons to believe that on the way up to birds, the lineage leading to caudipteryx branched off before the lineage leading to microraptor, and so the argument still holds. The fact that the theropod phylogeny is so uncertain, especially for the feathered dinosaurs, is admittedly a weakness of the claims for the specific stages of feather evolution.
A: Good catch! Yes caudipteryx even moves around the tree within that one lecture! Theropod phylogeny is highly debated and as new evidence emerges there are often changes. For caudipteryx there are two levels of confusion. It was originally proposed to be part of a sister group to the birds, but was later widely recognized to be an oviraptor. Oviraptors themselves were thought to be ornithomimids but are now placed within the maniraptor clade. My apologies for not having that updated in the birds lecture. Although, I would not test on this of course and it does give you a taste of the ephemeral reality of some parts of the tree.
Q: on the note about caudipteryx, I was wondering if you could further clarify something for me - I was studying by looking at the cladogram for feather evolution and so am now wondering whether caudipteryx is still seen as an example of stage 2-4 evolution of feathers. If they're placed in the maniraptor clade, then does that mean that the stage 2-4 evolution of feathers came after the ornithomimid clade and so around the same time as the evolution of stage 5 feathers?
A: Another great question! The phylogeny (branching order) within the maniraptors is unclear but I think there are a few reasons to believe that on the way up to birds, the lineage leading to caudipteryx branched off before the lineage leading to microraptor, and so the argument still holds. The fact that the theropod phylogeny is so uncertain, especially for the feathered dinosaurs, is admittedly a weakness of the claims for the specific stages of feather evolution.
Do we need to know the different birds?
Q: Question about the final. Do we have to know the different types of birds in the cladogram and their differences or do we simply need to know that the cladogram (like the saurichian cladogram on the website) ends with aves?
A: Yes, you do need to know the three non-living birds and their evolutionary novelties as presented in lecture... confuciusornis (pygostyle), Hesperonis (carpometacarpus), and the strange mononykus (carpometacarpus but not a pygostyle)
A: Yes, you do need to know the three non-living birds and their evolutionary novelties as presented in lecture... confuciusornis (pygostyle), Hesperonis (carpometacarpus), and the strange mononykus (carpometacarpus but not a pygostyle)
Monday, June 2, 2008
Tips for the Final?
Q; DO YOU HAVE ANY TIPS FOR THE FINAL. ARE YOU GOING TO EMPHASIZE ON CLADOGRAMS??. I HAVE TO START STUDYING ^_*. THANKS.
A: I strongly suggest the following strategy for studying.
1) Start by memorizing the cladograms including the branching order and all of the characters listed. You should fully understand the cladogram, i.e. how it represents the history of the lineages and which groups have which characters, etc.
2) Go through the lecture material with the cladograms at hand. Correlate where on the cladogram each animal discussed fits in. Make sure you understand (not memorize - that won't work) all of the additional concepts that we talked about. If there are slides or lines in the lecture notes that you don't fully understand, make of note of them and bring them to my or your TAs office hours.
3) There will probably be one or two questions on the final exam from the additional readings. If (and only if) you are going for a top score in the class, then you should go over the additional readings (in the ExtraReadings folder at the course website).
What scores get what grades
Q: I WOULD LIKE TO KNOW WHAT IS THE SCORE THAT I NEED TO GET TO GET AN A IN THE CLASS. I HAVE DONE ALL THE LABS SO FAR. IN THE MIDTERM I GOT 34/50 . IN THE SECOND MIDTERM I GOT 40/50.
A: I can't tell you exactly what it will take to get an A, but based on the distribution shown in the syllabus (mean for that year was 75%), your grades on midterm 1 and 2 would be approx. B- and A (I added 5% to your scores because our average was 5% lower, 70%). I would say that you would need to score over 80% on the final to get an A in the class - this assumes the class average for the final exam is 70%. If the class average is higher, you'll need a higher score of course. Also it's assumes that you got close to 100% on all of your labs (except for the one which will be dropped).
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