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GA Reassessment[edit]

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The reason for reassessment is inaccuracy regarding one possible cause of extinctions, linked to the extinction of basilosaurus: the later is believed to have become extinct 34 million years ago while megalodon's oldest remains are about 18 million years.

No where it is mentioned in the article that the extinction of the Basilosaurus has any linkage with that of the C. megalodon. It is just a reference example that factors such as "Climatic Upheavels" and "Shortage of Food" can cause demise of any marine species. Basilosaurus also went extinct due to similar reasons and of-course it happened much earlier. However, if some one feels that the reference is invalid and shall be removed than I have no issues with it. LeGenD (talk) 10:51, 31 March 2009 (UTC)[reply]
I have removed the controversial information from the main article. LeGenD (talk) 1:46, 31 March 2009 (UTC)

Comments from Philcha[edit]

I've done a few GA reviews and written a few GAs, both including zoology and paleontology topics. I would not pass Megalodon as a GA in its current state, but think the faults can be fixed by a determined editor within 2 weeks:

  • A lot of the writing is clumsy, sometimes bordering on ungrammatical, e.g. (only a limited sample, there are more):
    • "Due to notable similarities among the teeth of the great white shark, Carcharodon carcharias and megalodon, Agassiz proposed the genus, Carcharodon for megalodon" (section "Taxonomy").
    • "There is a major disagreement among scientists as to how C. megalodon should be classified.[1][2] The controversy is that whether C. megalodon is a close relative of the extant great white shark or whether the two species are distant relatives" could be condensed into one sentence.
    • In "According to Carcharocles proponents, Otodus obliquus evolved in to Carcharocles aksuaticus,[1][6] which evolved in to Carcharocles auriculatus,[1][6] which evolved into Carcharocles augustidens,[1][6] which evolved into Carcharocles chubutensis,[1][6] which eventually evolved into megalodon"
      • IMO should say e.g. "According supporters of classification as Carcharocles" --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
      • The multiple use of "evolved into" suggests a chronospecies. Is that what the sources are describing? If so, the article should say it explicitly. This seems to be what Ward proposed, but I don't know how widely it's accepted in the Carcharocles faction. If not, then e.g. "megalodon evolved from Otodus obliquus via ..." would leave open the possibility that the other species produced other descendant species and that there may have been chronological overlaps in the sequence. In fact I think it's prudent to do that anyway, and treat the chronospecies question as a separate issue. --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
    • "Carcharocles proponents also point out that the great white shark is more closely related to an ancient shark Isurus hastalis, the "broad tooth mako", than C. megalodon" is ambiguous - is I. hastalis more closely related to megalodon or the the Great White? --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
    • "Based on the study of the 4 million years old fossilized remains, the most complete yet found, of head elements of an ancient form of great white shark (discovered in Peru in 1988, and donated to the Florida Museum of Natural History in 2008)" is a longish sentence without a verb. --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
    • Needs to explain or work round tech terms, e.g. "centra" in "Anatomy and appearance", "dental formula" and related terms such as "mesial" in "Jaw dentition". --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
    • Needs to avoid WP:PEACOCK terms like "super predator" (in "Anatomy and appearance") and "colossal bite force" (in "Behavior"). In the case of bite force, comparisons with e.g. the Great White, Dunkleosteus & other large predatory ifish, a large croc, T rex and possibly Liopleurodon (if not grossly exaggerated by Walking with Dinosaurs) would be more informative and perhaps more impressive, e.g. if it had even half T rex' bite force megalodon would have been death at first bite if it got a solid hit. --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
    • The final para of "Extinction" looks like a repetition of the bullet list(s). --Philcha (talk) 13:47, 1 April 2009 (UTC)[reply]
      • I think that's enough about the prose for now.
  • A few of the sources are 2nd-rate, e.g. In Gedenken an Vito Bertucci. I'm quite flexible about this in non-academic subjects (IMO WP:RS has an academic and corporatist bias that causes difficulties in non-academic subjects), but this is a science article and there's little excuse for not using academic sources, or at least more "popular" articles by recognised experts or published by research / academic organisations like WHOI or UCMP.
  • That suggests to me that a thorough check of all the refs is needed. --Philcha (talk) 12:47, 9 April 2009 (UTC)[reply]

Hi, LeGenD, I see you're doing some serious work here. Pl leave a message here or at my Talk page when you think it's time for me to do a more detailed review. --Philcha (talk) 12:49, 11 April 2009 (UTC)[reply]

Philcha, Thank you for your patience. I have been going through some sources used in the main article to see if any errors still persist in the content of the main article or if more information could be added. Some content needs further improvement. I am up for the task and will correct such issues within this week. Once I am done, I will leave a message here for you. --LeGenD (talk) 09:51, 27 April 2009 (UTC)[reply]
Philcha, You shall conduct a more detailed review of the entire article and suggest more improvements, if necessary. It will make it easy for me to fix issues, if any still persist. Thank you! --LeGenD (talk) 11:58, 05 May 2009 (UTC)[reply]
I wish it was that simple. I got curious about how this article passed a GA review in the first place, and did some detective work:
The bottom line is that I think the original GA pass was invalid, and will ask someone more familiar with the mechanics to undo it (under the covers there are several pages, lists and categories that need to be kept consistent).
However I appreciate the work you've been putting into this, and will produce more detailed comments after I've tried to sort out the mess. My comments will not be as detailed as a full GA review, since I only got into this because Talk:Megalodon is on my watchlist following some comments I posted a while ago, and I'm busy with a complex article and a long, complex GA review.
If you disagree with my conclusion that Megalodon should never have been a GA, I suggest you raise the issue at WT:GAN - the most liekly result of this would be another reassessment. --Philcha (talk) 10:14, 5 May 2009 (UTC)[reply]
I've now raised the "invalid pass" issue at Wikipedia_talk:GAN#Megalodon_passed_as_GA_improperly.3F. I'm adding more detailed comments below.

Coverage[edit]

The article covers all the topics I'd expect an article about a fossil genus or species, and all the points that I was aware of from previous casual reading. I have not surveyed the scientifc literature to see if there are any other major issues that need to be covered, but I'm fairly confident that the article meets the GA criteria's requirement for "broad" coverage. --Philcha (talk) 10:43, 5 May 2009 (UTC)[reply]

Structure[edit]

In my opinion the structure is almost completely backwards. I think it makes much more sense to start with the evidence (the fossils) or perhaps the history of discovery, and that classification should be last, as it depends on the fossil evidence and on conclusion drawn from that evidence, e.g. reconstructions. For examples see Kimberella and Opabinia. So I'd go for the order: history of discovery; description of the fossils, including the time range ; reconstruction; lifestyle, behaviour & ecology; extinction (in this case the hypotheses depend on views of its ecological role, prey & hunting behaviour); classification. Since fixing this will very probably involve major changes, the rest of my comments are provisional and detailed review of the (new) sections will have to wait until the structure issue is resolved. --Philcha (talk) 11:13, 5 May 2009 (UTC)[reply]

Sources[edit]

  • Too many of the sources look like "some guy's web page". For scientific aspects of articles web pages are only usable if you can showe that they were created by an authority in the field (e.g. Ctenophore cites pages by Claudia E. Mills, but also at least 1 scientific journal article that she co-authored), or are published by a university or other reputable research organisation and are not the work of students (Mill's pages are hosted by a university, and if you root around that site you'll see that she's on the academic staff, not a student; in other articles I've used web pages from UCMP, the University of California Museum of Paleontology, which I notice Megalodon also uses). Scientific journal articles are the best sources, followed by books by people who've also published scientific journal articles, provided neither their articles not their books have been shown to be unreliable by other authorities in the field. --Philcha (talk) 11:13, 5 May 2009 (UTC)[reply]
  • The most widely used source is Mark Renz' book Megalodon: Hunting the Hunter. Renz is an experienced fossil finder and guide with a specific interest in sharks, but that does not prove that he's an expert on the analysis and classification of fossils. That does not mean he's not an expert, for example Gregory S. Paul started as an illustrator specialising in dinosaurs but his desire to reconstruct dinos accurately got him deeper and deeper into the science, and he's now well respected by scientists and has got articles published in scientific journals. That's the sort of thing you'd have to demostrate for Renz in order to use him as an authority. Even then it would be safer to widen the range of sources, to avoid concerns that Megalodon might be promoting one person's point of view by giving undue weight to his writings. --Philcha (talk)

Classification dispute[edit]

  • The whole section appears to be "he said ..., she said ...", like a kids' quarrel. You need to explain the reasons for the different views. That's a major reason why I suggested a different structure, because in that structure the article would already have explained the features found in the fossils. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • By showing only 1 cladogram you're supporting one point of view, which WP policy forbids. If there's a serious controversy you should give about equal prominence to at least the two most widely-cited views, which mneans that if you illustrate one with a cladogram you must do the same for the other, as at e.g. Evolutionary_history_of_life#Flowering_plants. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Megalodon within Carcharocles[edit]

  • If the megalodon lineage was a chronospecies, by definition it can't be a family tree as it has no branches. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • "his stunning revelation has received recognition from several shark researchers (e.g. J. Bourdon, L. Andrez, H. Capetta, V. I. Zhelezko, and V. A. Kozlov)" has 2 problems:
  • "his suggestion is given credence by many scientists due to some convincing evidence" is redundant (it cites 2 of the 3 sources cited by the next sentence) and looks like rhetoric. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • As it stands "One reason is that the teeth of I. hastalis and C. carcharias are remarkably similar in shape, differing only in that the former lack the characteristic serrations of the latter" is unconvincing, since teeth often convergently take similar forms in widely separated lineages - for example sabre-teeth have evolved several times, from Permian theriodonts to various Cenozoic carnivores, including the marsupial Thylacosmilus as well as the placental Smilodon; skulls and teeth of marsupial and placental carnivores often show conbergent evolution, e.g. the skull, jaws and teeth of the marsupial thylacine are very simliar to those of large canids such as wolves. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Anatomy and appearance[edit]

  • I was surprised to see that jaws are not included among the fossils, as vertebrate predators' jaws are usually pretty stong. Then I found what shark says about how shark jaws are strengthened without the use of bone. I think an explanation is needed of why shark jaws are less good candidates for fossilisation than one might expect. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Size estimation[edit]

  • Need to explain "enamel height", "in slant" and "slant height" (and any other uncommon terms) early in the section. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • This section could be a lot brifer: the writing can be made more concise; and I'm not sure it's necessary to gives details of every single estimate or formula. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • "may have attained astonishing sizes and" is WP:PEACOCK, and also redundant. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Jaw dentition[edit]

Recent findings from japan (almost complete natural set) shows that megalodon dental formula doesn't include intermediate tooth at the upper jaws, so the correct formula for upper jaw on this species is 3.0.7.4, that discovery directly links megalodon to the otodus lineage, putting on the Carcharocles genus. — Preceding unsigned comment added by Oxy75 (talk • contribs) 09:47, 2 September 2013 (UTC)[reply]

  • I'm not sure what this section contributes to the article. The only point at which it touches on a major aspect of the article is "However, in the case of the great white shark, the intermediate tooth does points mesially. This point has often been raised in the Carcharodon vs. Carcharocles debate regarding the megalodon and favors the case of Carcharocles proponents" --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]
  • What is an "artificial dental formula"? It could mean "pure guesswork" for all I know. I see the term is used without explanation in the web page cited, and specialists may understand the term, but WP is not written for specialists. --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Skeletal reconstruction[edit]

  • What does "the jaw was lined up with its nose like other early sharks" mean? And how early? IIRC the earliest shark fossils that give real info about anatomy are are Devonian, see Shark#Evolution. -Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Distribution, range and habitat[edit]

  • Citation needed for "The oceans were noticeably warmer during the Miocene and early Pliocene. This would have made it possible for this species to flourish around the world". --Philcha (talk) 12:49, 5 May 2009 (UTC)[reply]

Comments from Philcha (version 2, after major revision of article)[edit]

Start of review[edit]

Since there have been major revisions, I'll approach this as a new GA nomination. The rules for GA reviews are stated at Good Article criteria. I usually do reviews in the order: coverage; structure; detailed walk-through of sections (refs, prose, other details); images (after the text content is stable); lead (ditto). Feel free to respond to my comments under each one, and please sign each response, so that it's clear who said what.

When an issue is resolved, I'll mark it with  Done. If I think an issue remains unresolved after responses / changes by the editor(s), I'll mark it  Not done. Occasionally I decide one of my comments is off-target, and strike it out

BTW I've occasionally had edit conflicts in review pages, and to reduce this risk I'd be grateful if you'd let me know when you're most active, so I can avoid these times. --Philcha (talk) 17:59, 25 September 2009 (UTC)[reply]

Coverage[edit]

Structure[edit]

Links validity check[edit]

(to be done when any issues in the main text have been resolved) link checker

Check for disambiguation and other dubious wikilinks[edit]

(to be done when any issues in the main text have been resolved)

Use of images[edit]

(to be done when any issues in the main text have been resolved)

Lead[edit]

(to be done when any issues in the main text have been resolved)


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