שיחה:ממנצ'יזאורוס

Mamenchisaurus sinocanadorum

יש מחלוקת על ההערכה של 35 מטר כאורכו של Mamenchisaurus sinocanadorum. אני מצטט את הדיון מוויקיפדיה האנגלית (מקור):

I am highly skeptical of the dimensions given for Mamenchisaurus sinocanadorum. Assuming M. hochuanensis was 22 meters long, that would mean M. sinocandorum would have to be about 60% longer to be 35 meters long. However, if one looks at the measurements of the first four cervical vertebrae of these two species, one finds that M. sinocanadorum is nowhere close to being that much bigger than M. hochuanensis. The greatest discrepency between the two species is in the posterior width of the third cervical, where M. sinocanadorum is about 50% larger than M. hochuanensis. This is an outlier, however, in most dimensions, M. sinocanadorum is about 5-15% larger than M. hochuanensis. The mass estimate is also questionable. Assuming M. sinocanadorum was 35 meters long, and M. hochuanensis was 22 meters and 15 tonnes, isometry (assuming mass increases with the cube of length) predicts that M. sinocanadorum would way about 60 tons. Only if one assumes the maximum estimated mass of M. hochuanensis, 18 tonnes, does isometry predict anything like 75 tonnes. However, this 18-tonne figure for M. hochuanensis was made assuming that its density was 1, not 0.8, which is more likely for sauropod dinosaurs. If we assume M. sinocanadorum was 26 meters (which is what was estimated in the description paper, and I find much more likely), isometry predicts that it weighed roughly 25 tonnes. This seems a lot more believable given the dimensions of M. sinocanadorum. Ashorocetus (talk) 01:07, 4 June 2013 (UTC)

It's all Greg Paul's fault, you're right, M. sinocanadorum is no that much larger than the other species but the specimen that Paul mentions in his Field Guide is based on a skeletal mount of an undescribed specimen that the museum says is M. sinocanadorum. I'm all for removing it from the list on those grounds but I'm not sure how other people think. Mike.BRZ (talk) 04:59, 4 June 2013 (UTC)

גם לי נראה הנתון הזה מעורר ספק, כי Mamenchisaurus sinocanadorum הוא לא מין שנתגלה בשנים האחרונות ומספר גדול כזה, אורך של 35, היה מגיע לכותרות ולגופי ידע מהימנים כגון Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages (האנציקלופדיה של הולץ), אך שם הוא לא מופיע. לי אשית נראה שמדובר בטעות שהשתרשה איכשהו, אבל אשמח לתגובה מברי סמכא שבעלי גישה לספרות מחקרית בנושא. בברכה, MathKnight ✡ (שיחה) 22:21, 1 בספטמבר 2013 (IDT)