Re: [dinosaur] Dinosaur records

I don't think the categories "Smallest known adult non-avian dinosaur" and "Latest non-avian dinosaurs" make a whole lot of sense, either. Exactly what the word "non-avian" refers to is going to depend on (1) which of the existingÂdefinitions of "Aves" you decide to use and (2) what phylogenetic hypothesis you apply that definition to. These choices make the answer to the question arbitrary and meaningless. I can make M. zhaoianus into an avian, and so disqualify it from your list: just use Aves sensu Chiappe 1992 (as the name for theÂleastÂinclusive clade containing Archaeopteryx and modern birds), and apply that definition to the phylogenies of Xu et al. (2011), Godefroit et al. (2013), or Hartman et al. (2019). Or I can make enantiornithines into non-avian dinosaurs by using Aves sensu Gauthier & de Queiroz 2001 (as the name for the least inclusive clade containing all living birds), in which case Iberomesornis easily supersedes Microraptor. It's a word game that doesn't provide any biological insight. What does provide it is analyzing body size evolution in a phylogenetic comparative framework, in which birds are explicitly treated as one lineage of dinosaurs (Benson et al. 2014; Lee et al. 2014; Puttick et al. 2014).

On a more serious note, these categories exemplify two classic arguments against the use of paraphyletic groups like "non-avian dinosaurs": they (1) obscure the degree of morphological and ecological disparity attained by certain clades, and (2) introduce pseudo-extinctions into the fossil record. It says something pretty astonishing about the evolutionary history of the groups concerned that living artiodactyls feed on both grass (cattle) and giant squid (sperm whale), or that theropods have given rise to both 6-ton terrestrial apex predators (Tyrannosaurus) and 3-gram nectarivores that converge on insects in their locomotion and physiology (bee hummingbird). However, you won't realize this if you artificially remove part of that disparity and restrict the terms "artiodactyls" and "theropods" to what's left. True, speaking of "non-avian theropods" at least makesÂit explicit that this is what we are doing, but it doesn't fix the problem of doing it in the first place.

Similarly, asking about the last appearance of a taxon only makes sense if the taxon in question did in fact go extinct. Many individual dinosaur lineages did, but dinosaurs as a whole didÂnot; there are approximately 10,500 species of them still alive at this very moment, so the question simply doesn't apply.ÂParaphyletic groups obscure this point, since they can disappear from the fossil record not only as a result of a genuine extinction, but also because they simply morphed into something else (in this case, birds).

Refs:

Benson RBJ, Campione NE, Carrano MT, Mannion PD, Sullivan C, Upchurch P, Evans DC. 2014. Rates of dinosaur body mass evolution indicate 170 million years of sustained ecological innovation on the avian stem lineage.ÂPLOS Biol.Â12(5): 1â11.

Chiappe LM. 1992. Enantiornithine (Aves) tarsometatarsi and the avian affinities of the Late Cretaceous Avisauridae.ÂJ. Vert. Paleont.Â12(3): 344â350.

Gauthier JA, de Queiroz K. 2001. Feathered dinosaurs, flying dinosaurs, crown dinosaurs, and the name "Aves". 7â41ÂinÂGauthier JA, Gall LF, eds.ÂNew Perspectives on the Origin and Early Evolution of Birds: Proceedings of the International Symposium in Honor of John H. Ostrom. New Haven, CT: Peabody Mus. Nat. Hist.Â

Godefroit P, Demuynck H, Dyke GJ, Hu D-Y, EscuilliÃ F, Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China.ÂNature CommsÂ4(1): 1394.

Hartman S, Mortimer M, Wahl WR, Lomax DR, Lippincott J, Lovelace DM. 2019. A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight.ÂPeerJÂ7: e7247.

Lee MSY, Cau A, Naish D, Dyke GJ. 2014. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds. Science 345(6196): 562â566.

Puttick MN, Thomas GH, Benton MJ. 2014. High rates of evolution preceded the origin of birds.ÂEvolutionÂ68(5): 1497â1510.

Xu X, You H, Du K, Han F. 2011. AnÂArchaeopteryx-like theropod from China and the origin of Avialae.ÂNatureÂ475(7357): 465â470.

El miÃ., 23 de sep. de 2020 a la(s) 05:54, Mike Taylor (sauropoda@gmail.com) escribiÃ:

Here's something I wrote a while back on how impossible it is to say which is the "biggest dinosaur":
https://svpow.com/2015/10/20/which-was-the-biggest-dinosaur/

Short summary: we don't what was biggest and probably never will.

-- Mike.

On Wed, 23 Sep 2020 at 08:40, Poekilopleuron <dinosaurtom2015@seznam.cz> wrote:
Good day to all listmembers. Just a short question - would you agree with these? Feel free to make comments and corrections. Thank you in advance!

Largest known dinosaur: _Argentinosaurus huinculensis_ (35 to 40 m long, about 72 000 to 96 000 kg)

Largest known theropod: _Tyrannosaurus rex_ (12 to 13 m long, about 7700 to 10 200 kg)

Longest known theropod: _Spinosaurus aegyptiacus_ (14 to 18? m long)

Smallest known adult non-avian dinosaur: _Microraptor zhaoianus_ (about 0.434 kg)

Tallest known dinosaur: _Sauroposeidon proteles_ (16 to 18? m tall)

Longest neck: _Mamenchisaurus sinocanadorum_ (up to 16 meters?)...and perhaps also giant individual of _Barosaurus sp._

Largest/longest head: _Torosaurus latus_ (2.7 to 3.2? m)...also _Eotriceratops xerinsularis_, about 3 m long

Largest/longest arms: _Therizinosaurus cheloniformis_ (2.5 to 3.5? m)...also _Deinocheirus mirificus_, around 2.5 m

Longest claws: _Therizinosaurus cheloniformis_ (0.7 to 0.9 m excl. keratinous sheath)

Longest teeth: _Tyrannosaurus rex_ (30.5 to 33? cm)

Longest dinosaur bone: _Mamenchisaurus sinocanadorum_ cervical rib (4.1 m long)

Largest dinosaur footprint: "Broome sauropod" (1.7 m in diameter)

Largest theropod footprint: "Bolivian abelisaurid" (1.15 m long)

Smallest dinosaur footprint: _Dromaeosauriformipes rarus_ (about 1 cm long)

Largest dinosaur egg: _Macroelongatoolithus xixianensis_ (up to 61 cm long)

Smallest dinosaur egg: _Himeoolithus murakamii_ (about 4.5 x 2 cm)

Earliest known dinosaurs (with preserved skeletal material): Santa Maria Fm. dinosaurs (233.2 million years old)

Latest non-avian dinosaurs: Hell Creek, Scollard, Frenchman, Tremp Fms. (66.0 million years old)

David ÄernÃ