Talk:Sparassodonta

Untitled

Any idea how we can make the classification a bit cleaner or easier to read?. PaleoKaden (talk) 23:44, 12 July 2009 (UTC)

Never mind, I bolded some stuff, it is easier to read. PaleoKaden (talk) 21:01, 15 July 2009 (UTC)

Verifiability

This article needs better citation and legitimate sources (no blogs), preferably with properly formatted references. The idea that Sparassodonta and its constituent taxa are no longer viewed as marsupials is new to me: can someone link the first study where this split was formally made? Animalparty (talk) 21:53, 15 October 2013 (UTC)

I don't known in which study this statement was made for first time, but the blog cited in the article provides two references: Guillermo W. Rougier, John R. Wible and Michael J. Novacek. First Implications of Deltatheridium specimens for early marsupial history, Nature 396, 459-463(3 December 1998); here is a cladogram of the study where you can see that Borhyaenidae and the basal sparassodont Mayulestes are excluded from Marsupialia, and the another reference is Asher RJ, Horovitz I, & Sánchez-Villagra MR (2004). First combined cladistic analysis of marsupial mammal interrelationships. Molecular phylogenetics and evolution, 33 (1), 240-50, that is available here and show a similar cladogram for Mayulestes. And certainly this article needs a lot of work in another aspects.--Rextron (talk) 17:50, 17 October 2013 (UTC)

Ok, since the original link is dead, I've found the updated and expanded Tet. Zool. blog, (now at http://blogs.scientificamerican.com/tetrapod-zoology/2012/07/12/meet-the-borhyaenoids-2012/), which gives a lot more information and background. It appears the actual higher level classification is more contentious than the view presented here, including the name of the taxon itself! a couple salient points from the blog:

1) Another name that Ameghino coined later on (in 1894) – Borhyaenidae – ended up superseding Acyonidae, and the name we’re using for the group here (Borhyaenoidea) is based on that one*. Borhyaenoids have also been called sparassodonts (for Sparassodonta Ameghino, 1894), and while this name is used by some recent authors it hasn’t been used as much. They’ve also been called Borhyaeniformes Szalay, 1962 and Borhyaenomorphia Archer, 1984. - Suggests synonyms should be discussed.

2) If borhyaenoids are part of Didelphimorphia, then they’re part of the marsupial crown-group and can properly be considered part of Marsupialia. If they’re not part of Didelphimorphia, the competing hypothesis puts them outside the marsupial crown-group, meaning that they’re stem-marsupials, or non-marsupialian metatherians- This suggests a controversy, and should be presented as such.

The comments in the article, and Mr. Nash's responses, also illustrate the controversial placement of these animals. I think in the interest of impartiality the issue deserves more discussion. I haven't looked at the studies yet referenced in the Tet. Zool. blog, but my hunch is they also show a much more nuanced picture. Animalparty (talk) 22:03, 24 October 2013 (UTC)

Prothylacinidae

The recent revision for Forasiepi (2009) makes Prothylacinidae (or Prothylacininae) a paraphyletic clade. But it implies that this group must have its own article to explain their taxonomic history? or it could be added in Sparassodonta or in a future article of Borhyaenoidea?--Rextron (talk) 20:10, 7 December 2013 (UTC)

I don't think Prothylacinidae necessarily needs its own article if it can be succinctly summarized in this one, as has been done by the anonymous editor(s) who've made great recent expansions. On that note, I'd like to publicly acknowledge & thank the recent contributions. --Animalparty-- (talk) 17:53, 9 December 2013 (UTC)

As the person who has made the recent expansions, I'd like to thank you for your thanks. I'm sorry I did the expansions anonymously, I have a Wikipedia account, but I forgot my password and Wikipedia will not send me a replacement, so I had to edit the article through three different computers 184.56.238.8 (talk) 23:46, 10 December 2013 (UTC)

I want to thank you too for your contributions in this article, I hope you can edit with a account again. Then for now we can leave to Prothylacynidae without an article, and maybe make more articles of sparassodont genera.--Rextron (talk) 01:20, 12 December 2013 (UTC)

Extinction

Only one study is cited as evidence for the new view on the group's extinction; is one study alone really enough to overturn the previous view? Can we really assume that there are no sufficient gaps in the fossil record to account for divergent dates between last known appearance and first known arrival of competing species?

Coconutporkpie (talk) 03:38, 14 November 2014 (UTC)

Is not the only study, but is the most recent and is authored by experts in these animals. I would ask if you known any recent study that shows evidence of sparassodonts lived after the Chapadmalalan age? In all the recent literature is show that Thylacosmilus was the last of the group, and the main invasion of carnivoran placentals into South America occured after, in the early Pleistocene (2,5 ma). Also, one of the supposed last sparassodonts, Parahyaenodon, actually is a procyonid. The abstract of the paper about Parahyaenodon says something interesting: "Based on these results and in the first records of carnivorous placental immigrants in South America, it is evident that there was no "competitive displacement" between metatherian and eutherian carnivores: there is a gap of no less than four Ma between the extinction of the last Borhyaeninae and the arrival of their alleged ecological counterparts, the Carnivora." (the paper is here, although is in Spanish: [1] ) The previous view was based in a insufficient fossil record of the Pliocene in South America, and that idea persisted in several authors like Simpson and Larry Marshall until the 80's. Also, currently is well established that sparassodonts were reduced in diversity since the middle Miocene, which agrees with the reduction or extinction of several others lineages of South American fauna.--Rextron (talk) 18:49, 14 November 2014 (UTC)

If all the recent literature does indeed support that conclusion, then it should be easy to cite more than one source for it. Otherwise, the language of the article should be altered to reflect the possibility that the source cited could be wrong. As an example of how evidence can lead to mistaken conclusions, the coelacanth disappeared from the fossil record for millions of years, yet it apparently existed all along.

This article and Thylacosmilus present inferences based on fossil evidence as though they were proven facts. It is my understanding that science does not deal with absolute proof, but rather the most likely explanation (see Scientific evidence#Concept of "scientific proof").

Coconutporkpie (talk) 22:11, 15 November 2014 (UTC)

Exists another articles, some of them in Spanish, that could be added (and I just to cite one in my previous comment). The another "possibility" is not mentioned in recent studies about sparassodonts, if I'm not wrong. As far I known science works with the known facts and the inferences that is reasonable to have from these. We simply don't have any post-Chapdamalalan sparassodont, and there is evidence of their decline after the Miocene, and in Wikipedia the editors must work with the published information, not with they want to be. That's why I ask you in first place if you known something about new evidence. If would exist a debate between the paleontologists about this issue, or reports of possible new findings, certainly it must added to the article, when it will be published in reliable sources. After all, the advantage of the wiki articles is that these could be improved with new information if it occurs, right? --Rextron (talk) 06:16, 16 November 2014 (UTC)