Re: Most dinosaurs were scaly

["Thomas R. Holtz, Jr." <tholtz@umd.edu>]

Actually, Mickey's objection wasn't. His objection was that if you only
coded small-bodied animals. The presence of large-bodied animals with fuzz
is a different issue.

And another issue ignored in this is that NOT ALL SEDIMENTS ARE EQUAL!
Optimize the same data for only lacustrine/lagoonal vs. coarser seds and
you get additionally different pictures.

Furthermore, a point I have made elsewhere: how well does fuzz/hair
fossilize in non-shale anyway? When we have skin impressions of larger
bodied Cenozoic mammals, how often do they show fur or hair?

But I don't think anyone disagrees that the ancestral condition excludes
scale. This isn't a mutually-exclusive binary situation: organisms
wouldn't have JUST fuzz or JUST 'scale'.

And at this point, I strongly suggest we wait for certain Siberian
material to be published; it should be soon-ish and has a great bearing on
the entire issue.

On Mon, December 30, 2013 7:57 pm, Jura wrote:
> I'd say your objection regarding body size has been made moot by the
> discovery of Yutyrannus (i.e., Yutyrannus was a large animal that showed
> no sign of reduced body covering).
>
> Jason
>
>
>
> ----- Original Message -----
>> From: Mickey Mortimer <mickey_mortimer111@msn.com>
>> To: "dinosaur@usc.edu" <dinosaur@usc.edu>
>> Cc:
>> Sent: Monday, 30 December 2013 7:23 PM
>> Subject: RE: Most dinosaurs were scaly
>>
>> Not to be too harsh, but you rather completely ignored my objection
>> regarding
>> body size.  Do the authors take this into account?  Do you think it's
>> worthwhile?  As I said before "In other words, it's obvious if you just
>> plug in known skin coverings
>> over a cladogram, scales will be the ancestral state for Dinosauria."Â 
>> If
>> all the authors do is test a hypothesis based on faulty assumptions to
>> find an
>> answer we all know would be found, then I fail to see how it could be
>> the best
>> poster at SVP.
>>
>> Mickey Mortimer
>>
>>
>> ----------------------------------------
>>>  Date: Mon, 30 Dec 2013 15:45:16 -0800
>>>  From: pristichampsus@yahoo.com
>>>  To: dinosaur@usc.edu
>>>  Subject: Re: Most dinosaurs were scaly
>>>
>>>  I found this to be the best poster at SVP this year. Ever since the
>> discovery of structures associated with Tianyulong and (to a lesser
>> extent) that
>> one Psittacosaurus individual, there seems to be a growing trend in
>> dinosaur
>> paleontology to assume that all dinosaurs were filamented (all
>> ornithodirans
>> even), in spite of a large collection of scale impressions from all
>> major
>> lineages. Barrett and Evan's analysis represents an actual test of this
>> hypothesis. That neither parsimony analysis nor max likelihood (the
>> latter of
>> which is more amenable to reversals) found filaments to be ancestral to
>> dinosaurs suggests that ancestrally scaly dinos is still the most
>> parsimonious
>> explanation. Admittedly, without data on the tree support values
>> (available for
>> the max likelihood tree at least) or a more detailed look at the methods
>> we can
>> only say so much about the
> ould caution against arguments for unique scale-filament intermingling,
>> based on hair distribution in armadillos. Armadillo "scales" are not
>> actually scales but are a unique form of agglutinated hairs (Wu et al.
>> 2004).
>> Pangolins are even weirder as their armour seems to have evolved from
>> the same
>> germinative layers as claws/nails (Spearman 1967). In fact, according to
>> evo-devo studies synapsids probably never had "true" scales (=
>> sauropsid type) as beta-keratin (a
>> been found in the integument of mammals (although pangolins do have an
>> analogue).
>>>
>>>  As for whether we might be mislead into thinking some pebbly skin
>>> texture
>> is actually scaly, it is a cause for concern. Dinosaur skin impressions
>> tended
>> not to receive much description unless they involve filaments. It has
>> only been
>> rather recently that there has been an interest in the scaly coverings
>> of
>> dinosaurs, with Bell (2012) and Davis (2012) offering insights into
>> scale
>> structures and distribution among dinosaurs. Paik et al. (2010) gave the
>> only
>> analysis I'm aware of regarding potential misinterpretation of
>> lithological
>> structures as being integumental,
>>>  can occur. A key factor to determining scales vs. lithology (or pebbly
>> skin) seems to be the regularity of the structures. Pebbly skin has
>> raises and
>> cracks that are randomly distributed. Similarly, rainprints and ripple
>> marks may
>> be more uniform but don't interlock and often vary greatly in size from
>> print to print. Scaly skin, on the other hand, tends
>>>  to show a more regular patterning of interlocking polygons.
>>>
>>>  It's unfortunate that this is only a press release. I talked with Paul
>> at SVP about this being coming out as a paper and he mentioned that it
>> would be
>> published soon. It's too bad this press release may take away a lot of
>> the
>> impact.
>>>
>>>
>>>  Jason
>>>
>>>
>>>  References
>>>
>>>  Bell, P.R. 2012. Standardized Terminology and Potential Taxonomic
>>> Utility
>> for Hadrosaurid Skin Impressions: A Case Study for Sauroplophus
> 95.
>>>
>>>  Davis, M. 2012. Census of Dinosaur Skin Reveals Lithology may Not Be
>>> the
>> Most Important FActor in Increased Preservation of hardorsaurid Skin.
>> Acta.
>> Paleontological Polonica.
>>>
>>>  Paik, S., Kim, H.J., Huh, M. 2010. Impressions of Dinosaur Skin from
>>> the
>> Cretaceous Haman Formation in Korea. Journal of Asian Earth Sciences
>> 39:270â??274.
>>>
>>>  Spearman, R.I.C. 1967. On the Nature of the Horny Scales of the
>>> Pangolin.
>> Journal of the Linnean Society (Zoology). 46(310):267â??273.
>>>
>>>  Wu, P., Hou, L., Plikus, M., Hughes,
>> Suksaweang, S., Widelitz, R.B., Jiang, T-X, Chuong, C-M. 2004. Evo-Devo
>> of
>> Amniote Integuments and Appendages. International Journal of
>> Developmental
>> Biology. 48:249â??270.
>>>
>>>
>>>
>>>
>>>
>>>> ________________________________
>>>>  From: Zach Armstrong <zach.armstrong64@yahoo.com>
>>>> To: "dinosaur@usc.edu" <dinosaur@usc.edu>
>>>> Sent: Saturday, 28 December 2013 4:53 PM
>>>> Subject: Re: Most dinosaurs were scaly
>>>>
>>>>
>>>>
>>>>
>>>> I concur with what Mickey has said. I would also like to raise the
>> question of how confidant we can be that the all the scales of dinosaurs
>> are
>> true scales, and are not epidermal structures secondarily derived from
>> feathers
>> due to evo-devo mechanisms?
>>>>
>>>>
>>>> At least some evo-devo studies suggest that the reticula scales on the
>> plantar surface of avian feet are actually developmentally stunted
>> feathers. To
>> quote from Dhouailly (2009), "[R]eticula are not true cutaneous
>> appendages,
>> and appear to be feathers
>>>> arrested in the initiation step of their morphogenesis: formation of a
>>>> slight bump, without a pla
>>>  lar suggestions were made by Sawyer and Knapp (2003).
>>>>
>>>> At least some non-scale epidermal structures in modern avians
>> morphologically mimic scales too. For instance, the facial wattles of
>> Philepitta
>> schlegeli (Schlegel's Asity) have an appearance to me that mimics
>> scales:
>> http://thefeaturedcreature.com/wp-content/uploads/2012/10/Screen%2Bshot%2B2011-06-05%2Bat%2B7.26.20%2BPM2.png
>>> A similar thing can be said about the bare skin on the head and neck of
>> Coragyps atratus (Black Vulture):
>> http://en.wikipedia.org/wiki/File:Coragyps-atratus-002.jpg
>>>>
>>>> If all we had were fossilized impressions of these bare skin
>>>> structures,
>> might we erroneously conclude they were true scales?
>>>>
>>>> I also think inferring from osteoderms in thyreophorans and sauropods
>> that their ancestors never had filamentous integumentary appendages
>> (FIAs) might
>> be misleading. Hair sprouts amongst the osteoderms of armadillos for
>> instance:
>> http://upload.wikimedia.org/wikipedia/commons/b/b4/Nine-banded_Armadillo.jpg
>> Do
>> fossil cingulates
>> derms? Seems unlikely.
>>>>
>>>>
>>>> The same might be true for scaled dinosaurs, even those with
>>>> osteoderms.
>> Additionally, feathers erupt from scutate scales in some birds on
>> occasion.
>> Sawyer & Knapps (2003) noted, "The growth of feathers from the distal
>> ends of scutate scales occurs occasionally in normally scaled [chicken]
>> breeds
>> such as White Plymouth Rock and White Leghorn.
>>>> have been observed growing from the tips of the definitive scale
>>>> ridges
>> at 12 days of incubation." So scales and feathers intermingling are not
>> de
>> facto impossible, although there appears to be significant developmental
>> constraints. Maybe these constraints were more relaxed during the
>> initial
>> evolution of FIAs in dinosaurs.
>>>>
>>>> -Zach
>>>>
>>>>> ________________________________
>>>>
>>>>>  From: Mickey Mortimer <mickey_mortimer111@msn.com>
>>>>> To: "dinosaur@usc.edu" <dinosaur@usc.edu>
>>>>> Sent: Friday, December 27, 2013 11:48 PM
>>>>> Subject: RE: Most dinosaurs were scaly
>>>>>
>>>>>
>>>>> Is it just me, or does this study seem to suffer fr
>>>  aively assuming body covering doesn't covary with other factors we can
>> test?  In other words, it's obvious if you just plug in known skin
>> coverings
>> over a cladogram, scales will be the ancestral state for Dinosauria. 
>> No
>> one's ever doubted that, Greg Paul included.  The additional factor
>> which
>> has been
> rk is of course size.  What happens if
>> you only plot small specimens on the cladogram?  Ornithischians are all
>> fuzzy/spiny, and sauropodomorphs are unknown unless the titanosaur
>> embryos
>> count.  Even if the latter do count, Sciurumimus makes theropods
>> primitively
>> fuzzy despite Juravenator, so that's ambiguous basal Saurischia and
>> fuzzy
>> basal Dinosauria, which only gets more support if pterosaurs are
>> avemetatarsalians.  Maybe Barrett and Evans include a caveat about this
>> assumption, but since taking it into account nullifies their entire
>> conclusion,
>> I don't think
>>>> it could help.  This isn't even getting into the metabolic and
>> growth evidence that
>>>>> shows increasingly basal archosauromorphs weren
>>>>> 'reptiles'.  You might as well determine ornithischians
>> don't have cheeks based only on their lack in birds, crocs and
>> lepidosaurs.
>>>>>
>>>>> Mickey Mortimer
>>>>>
>>>>>
>>>>> ----------------------------------------
>>>>>>  Date: Fri, 27 Dec 2013 10:13:58 -0800
>>>>>>  From: bcreisler@gmail.com
>>>>>>  To: dinosaur@usc.edu
>>>>>>  Subject: Most dinosaurs were scaly
>>>>>>
>>>>>>  From: Ben Creisler
>>>>>>  bcreisler@gmail.com
>>>>>>
>>>>>>
>>>>>>  A news item and the original abstract from the 2013 SVP
>> meeting:
>>>>>>
>>>>>>  Nature news:
>>>>>>
>>>>>>
>> http://www.nature.com/news/feathers-were-the-exception-rather-than-the-rule-for-dinosaurs-1.14379
>>>>>>
>>>>>>
>>>>>>  The abstract from the SVP Meeting:
>>>>>>
>>>>>>
>>>>>>  Poster Session III (Friday, November 1, 2013, 4:15 - 6:15 PM)
>>>>>>  DINOSAUR INTEGUMENT: WHAT DO WE REALLY KNOW?
>>>>>>  BARRETT, Paul, The Natural History Museum, London, United
>> Kingdom; EVANS,
>>>>>>  David, Univ of Toronto at Mississauga, Toronto, ON, Canada
>>>>>>
>>>>>>  Osteoderms and scaly skin impressions are historically well
>> known in n
>>>  saurs
>>>>>>  these structures,
>>>>>>  many dinosaur taxa possessed other integumentary features,
>> including a
>>>>>>  range of â??quills,'
>>>>>>  filaments, and feathers in non-avian theropods and
>> ornithisc
> only regarded as a synapomorphy of either
>> coelurosaurian or
>>>>>>  tetanuran theropods, but some authors have gone further, using
>> the presence of
>>>>>>  ornithischian feather-like structures to suggest that these
>> structures
>>>>>>  are plesiomorphic for
>>>>>>  Dinosauria. This inference has wide-ranging implications for
>> dinosaur
>>>>>>  biology and
>>>>>>  evolution.
>>>>>>  However, to date, no studies have attempted to assess
>> rigorously the
>>>>>>  evolution of
>>>>>>  dinosaur integumentary structures within a broad phylogenetic
>> context.
>>>>>>  We compiled a
>>>>>>  complete database of all epidermal integumentary structures
>> reported
>>>>>>  in dinosaurs, by
>>>>>>  major body region, in order to investigate the origin of
>> feather
>>>>>>  homol
>>>> nd the
>>>>>>  evolution of integumentary structures in the clade
>>>>>>  definitively present in
>>>>>>  virtually all major ornithischian clades. This, and the
>> presence of
>>>>>>  extensive armour in
>>>>>>  thyreophorans suggests that genasaurian skins were primitively
>> scaly. Similarly,
>>>>>>  sauropodomorphs lack evidence for anything other than scales or
>>>>>>  osteoderms. Fitch
>>>>>>  optimization of integument types on dinosaur phylogenies shows
>> that there is no
>>>>>>  unequivocal support for inferring a deep origin of feather-like
>>>>>>  structures, a result
>>>>>>  supported by maximum likelihood ancestral state reconstructions
>> for
>>>>>>  these characters.
>>>>>>  The structures in Tianyulong and Psittacosaurus are best
>> regarded as
>>>>>>  autapomorphic
>>>>>>  integumentary modifications, and there is currently no strong
>> evidence
>>>>>>  that these features
>>>>>>  are feather homologs. Further work on the chemical composition
>> of
>>>>>>  these structures, and
>>>>>>  those in several non-coelurosaurian theropods, is needed.
>> Although
>>>>>>  ornithodirans exhibit
>>>>>>  a range of integumentary novelties that may be related to the
>> origin
>>>  re currently the only dinosaurs that display unequivocal e
>>>>>>  feathers and their
>>>>>>
> logs.
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>  Â Â Â  Â Â Â   Â Â Â  Â   Â Â Â  Â Â Â  Â 
>>
>


Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA