Feathered T-rex video: Excellent!*

The best video* I’ve seen on feathered dinosaurs.
*But note: their gliding Anchiornis forgot how to flap. Flapping came first. Then flapping with bipedal climbing. Then flapping with flying. Birds don’t come by gliding except to rest while airborne. Same with bats (if any glide ever). Same with pterosaurs. Let’s take gliding out of the equation for the origin of flight. That’s widespread antiquated thinking not supported by evidence. If you glide you do not flap. If you flap, some of your ancestors may learn to glide.

Click here or on the image to play.

Hypsibema missouriensis – a Late Cretaceous Appalachia duckbill dinosaur

Figure 1. Model of Hypsibema missouriensis, a hadrosaurid dinosaur

Figure 1. Model of Hypsibema missouriensis, a hadrosaurid dinosaur

Hypsibema missouriensis
(Cope 1869; Gilbert and Stewart 1945; Gilbert 1945; Baird and Horner 1979; Darrough et al. 2005; Parris 2006; Campanian, 84-71 mya, Late Cretaceous) is a fairly large hadrosaurid dinosaur discovered in 1942, at what later became known as the Chronister Dinosaur Site near Glen Allen, Missouri. At present this literal pinprick in the map of Missouri is the only site that preserves dinosaur bones.

Figure 2. Where the Hypsibema maxilla chunk came from on the skull of Saurolophus.

Figure 2. Where the Hypsibema maxilla chunk (Figure 3) came from modeled on the skull of Saurolophus.

Small pieces of broken bone and associated caudals and toes
were first discovered when digging a cistern. They had been found about 8 feet (2.4 m) deep imbedded in a black plastic clay. The area is in paleokarst located along downdropped fault grabens over Ordovician carbonates.

Gilmore and Stewart 1945 described a series of Chronister caudal centra (now at the Smithsonian) as sauropod-like, reporting, “The more elongate centra of the Chronister specimen, with the possible exception of Hypsibema crassicauda Cope, and the presence of chevron facets only on the posterior end appear sufficient to show that these vertebral centra do not pertain to a member of the Hadrosauridae.”

First named Neosaurus missouriensis,
the caudals were renamed Parrosaurus missouriensis by Gilmore and Stewart 1945 because “Neosaurus” was preoccupied. The specimen was allied to Hypsibema by Baird and Horner 1979.

Figure 3. Back portion of a Hypsibema maxilla showing tooth root grooves and cheek indention close to jugal.

Figure 3. Back portion of a Hypsibema maxilla showing tooth root grooves and cheek indention close to jugal.

Back in the 1980s
I enjoyed going to the Chronister site with other members of the local fossil club, the Eastern Missouri Society for Paleontoogy. I was lucky enough to find both a maxilla fragment (Fig. 3) and a dromaeosaurid tooth. I remember the horse flies were pesky and  one morning, before the other members got there, I was met by a man with a shot gun who relaxed when I identified myself. A friend found a series of hadrosaur toe bones, each about as big as a man’s hand (sans fingers). The bone was so well preserved you could blow air through the porous surfaces.

Baird D and Horner JR 1979. Cretaceous dinosaurs of North Carolina. Brimleyana 2: 1-28.
Cope  ED 1869.
Remarks on Eschrichtius polyporusHypsibema crassicaudaHadrosaurus tripos, and Polydectes biturgidus“. Proceedings of the Academy of Natural Sciences of Philadelphia 21:191-192.
Darrough G; Fix M; Parris D and Granstaff B 2005.
 Journal of Vertebrate Paleontology 25 (3): 49A–50A.
Gilmore CW and Stewart DR 1945. A New Sauropod Dinosaur from the Upper Cretaceous of Missouri. Journal of Paleontology (Society for Sedimentary Geology 19(1): 23–29.
Gilmore CW 1945. Parrosaurus, N. Name, Replacing Neosaurus Gilmore, 1945. Journal of Paleontology (Society for Sedimentary Geology 19 (5): 540.
Parris D. 2006. New Information on the Cretaceous of Missouri. online

bolinger county museum of natural history
More info and links

Carrano et al. 2012: Basal Tetanurae interrelations

The classification of theropods
has been going on for a hundred years, spurred every year by the discovery of new taxa. Before computers the main division was based on size. The use of software has clarified that issue.

Several years ago,
Carrano, Benson and Sampson (2010) undertook a large study of theropod dinosaurs, focusing on the basal Tetanurae (closer to birds than to Ceratosaurus), up to and not including Coelurosauria (Compsognathus, Ornitholestes and further derived taxa including birds and kin. The authors note: “Tyrannosauridae is now universally included within Coelurosauria (Novas 1991a; Holtz 1994a), whereas ceratosaurs and coelophysoids are basal to Tetanurae.”

They also note, “The placement of many individual taxa within any of these frameworks also varies. ‘Megalosaurs’ pose an even greater and more complex problem. Many of the taxa that have at one time been referred to Megalosauridae have now been dispersed elsewhere, but a large number of putative megalosaur species remain.”

“In summary, although a great deal of progress has been achieved in recent years (measured mainly by increased consensus), several points of uncertainty remain in tetanuran phylogeny and are therefore of primary interest here. These are: (1) whether spinosauroids (= megalosauroids) and allosauroids form a clade, or are serially arranged outside Coelurosauria; (2) whether ‘megalosaurs’ form a valid clade and, if so, its membership; (3) placement of fragmentary forms of potential geographic and temporal importance; and (4) placement of relatively well known but problematical forms (e.g. Cryolophosaurus, Marshosaurus, Monolophosaurus, Neovenator and Piatnitzkysaurus).”

Their work involved firsthand examination
of hundreds of theropod specimens, but no reconstructions were made. Looking at hundreds of specimens is a very good thing, but reconstructions are the notes that let the reader know how bones were interpreted. Without them one must laboriously go through the raw numbers to check for accuracy. No one wants to do that. Reconstructions are a sort of shorthand enabling one to quickly make comparisons of hundreds of characters.

Zanno and Makovicky (2013) recovered a virtually identical theropod tree topology.

In counterpoint
The large reptile tree (subset: Fig. 1) keeps growing without changing topology. Perhaps it offers some insight into theropod relations. Some of the stability of this tree may be due to the inclusion set. Some taxa are tested together here for the first time. There are fewer theropod taxa here than in the works referenced below, but several theropod taxa are included here that are not included in the referenced works.

Figure 1. Basal theropod subset of the large reptile tree showing troodontids basal to birds and separate from dromaeosaurs.

Figure 1. Basal theropod subset of the large reptile tree showing troodontids basal to birds and separate from dromaeosaurs. See the large reptile tree for included taxa not shown here.

Carrano MT, Benson RBJ and Sampson SD 2012. The phylogeny of Tetanurae (Dinosauria: Theropoda). Journal of Systematic Palaeontology 10(2):211–300.
Zanno L and Makovicky PJ 2013. Neovenatorid theropods are apex predators in the Late Cretaceous of North America. Nature Communications | 4:2827 | DOI: 10.1038/ncomms3827 |www.nature.com/naturecommunications

They’re out there somewhere!

Back in the ’90s, 
I built several full scale prehistoric reptile models out of wood, wire, foam, glass (eyes) and what have you. Two of them are shown here (Fig. 1).

Figure 1. Baby Camarasaurus and featherless Deinonychus models built by David Peters in the 1990s.

Figure 1. Baby Camarasaurus and featherless Deinonychus models built by David Peters in the 1990s.

At the time, 
like the the extinct Steve Czerkas and the extant Charlie McGrady, I wanted to be build dinosaurs, not just illustrate them in books. At the time, St. Louis did not have a Science Museum and that’s when (so I was told) you are supposed to get in on the ground floor. Also at the time the late sculptor Bob Cassilly was building squids, pterosaurs, sharks and rays for the St. Louis Zoo based on illustrations in my book Giants. (Bob was instrumental in bringing Sharovipteryx, Longisquama and the other Russian dinosaur exhibit to St. Louis.) Alas, that phase fizzled and the writing of papers followed. Early on you’re driven by enthusiasm and reined in by naiveté. In evolutionary terms, it worked out for that time and place.

Along with
the baby Camarasaurus and adult Deinonychus, I built a plesiosaur, Tanystropheus, fuzzy Dimorphodon, Pterodactylus and the several pterosaur skeletons seen here. The fleshed out sculptures went to the AMNH in NYC. The baby sauropod went to Martin Lockley in Colorado. The skeletons all went to Mike Triebold. Many artists want to see their art hanging in museums. Well, it happened to me, sort of, with those pterosaur skeletons. They’re out there, all over the world. The AMNH ultimately decided to display only skeletons in their renovated prehistoric displays and sold off what they had purchased.

I have no idea
where the various pieces are now or what shape they are in. But it was fun for awhile and the mailman probably told his kids about the address that had dinosaurs under the carport. Now a longer list of illustrated and animated prehistoric reptiles can be found on the Internet here.

Agilisaurus and the origin of the Pachycephalosauridae

Stegoceras validum (Lambe 1902; Late Cretaceous, Late Campanian; 75mya; 2m length; Fig. 1) was a basal dome-head dinosaur, or pachycephalosaur. Traditionally pachycephalosaurs have been linked to to stegosaurs, like Stegosaurus, troodontids like Sinornithoides, and ceratopsians, like Triceratops, but those are not supported in the large reptile tree (subset Fig. 4).

In the large reptile tree
Stegoceras was recovered as a sister to Agilisaurus (Peng 1990; ZDM 6011; Middle Jurassic; 1.2m length; Figs. 2-4).

In Stegoceras
the nares face somewhat forward, as in Agilisaurus. Similarly the forelimbs are tiny on this biped. The palpebral bones are incorporated into the skull itself. The antorbital fenestra is no longer visible. The dorsal and caudal ribs are quite wide, giving this dinosaur a wider than deep torso and tail first noted by Greg Paul, who kindly provided permission for his famous reconstruction (Fig. 1). The posterior tail is stiffened with ossified tendons originally thought to be gastralia.

Figure 1. Stegoceras, a basal pachycephalosaur from the Mid-Cretaceous is derived from a sister to Agilisaurus.

Figure 1. Stegoceras, a basal pachycephalosaur from the Mid-Cretaceous is derived from a sister to Agilisaurus.

Sullivan 2003 writes,
“Pachycephalosaurian dinosarus, known primarily fro their unusually thickened crania, are perhaps the most enigmatic and poorly understood dinosaurs.” Sullivan, like many traditional paleontologist, used ceratopsids for his phylogenetic outgroup. Traditionally pachycephalosaurs and ceratopsids have been lumped in the clade “Marginocephalia” (Sereno 1986). The large reptile tree (subset Fig. 3) does not support that nesting. Instead, the odd Agilisaurus nests with Stegoceras. It shares many traits including incipient anteriorly facing nares, small fore limbs and a long tail. The presence of upper temporal fenestrae in Stegoceras,though tiny, mark this as a basal pachycephlosaur.

Sereno (1986)
based the taxon on four synapomorphies (listed before the publication of Agilisaurus, which does or could share all 4 traits):

  1. narrow parietal shelf
  2. posterior squamosal shelf
  3. short posterior premaxillary palate
  4. short postpubic process (the original retroverted pubis sans the prepubic process)

The most basal member of the Marginocephalia
is reported to be Stenopelix, which we looked at earlier here. With current data,
the clade “Marginocephalia” has no utility because pachycephalosaurs do not nest with ceratopsians to the exclusion of all other taxa.

Sullivan continues
“It is clear that pachycephalosaurids appear rather abruptly in the fossil record (the Santonian). The origin of this group, and the directionality in dispersals of its taxa can only be speculative based on current (2003) information.”

Figure 1. The skull of Agilisaurus (Late Jurassic) provides the bauplan for the skull of more derived pachycephlosaurs, like Stegoceras.

Figure 1. The skull of Agilisaurus (Late Jurassic) provides the bauplan for the skull of more derived pachycephlosaurs, like Stegoceras. Note the anteriorly facing nares. The palpebral bone is in two parts here.

Agilisaurus is an ornithischian oddball.
And, as in other phylogenetic enigmas, like Longisquama and Sharovipteryx, the oddballs (in this case, Agilisaurus + pachycephlosaurs) nest together. The enigmatic structures suddenly become synapomorphies when sister taxa are found to share apparent autapomorphic (unique) traits.

Figure 3. Agilisaurus, like Stegoceras, was a biped with tiny forelimbs and a long tail, providing the blueprint for later pachycephalosaurs.

Figure 3. Agilisaurus, like Stegoceras, was a biped with tiny forelimbs and a long tail, providing the blueprint for later pachycephalosaurs. Note the broad fronts and tiny parietals.

The large and broad frontals
of Agilisaurus, together with the relatively small parietals are precursor traits to the dome skulls of pachypleurosaurs. At this point, and with the limited number of taxa in the ornithischian subset of the large reptile tree, this is how relationships are recovered. Xu et al. 2006 in their paper on Yinlong, recovered Agilisaurus basal to heterodontosaurs in the branch leading to their “Marginocephalia.”

Figure 4. The phytodinosauria. Here Stegoceras and the pachycephalosaurs nest with the Middle Jurassic Agilisaurus.

Figure 4. The phytodinosauria. Here Stegoceras and the pachycephalosaurs nest with the Middle Jurassic Agilisaurus.

One of the problems traditional paleontologists have
with the Ornithischia is they don’t know which taxa are basal. They often use Lesothosaurus, rather than Chilesaurus and Daemosaurus as a basal taxon. Here Lesothosaurus is basal to Stegosaurus through Scutellosaurus. We talked about Chilesaurus earlier here. Traditional paleontologists don’t recognize the clade Phytodinosauria, either. When they do, everything will become clear.

I’d like to know more about
Micropachycephylosaurus, a tiny taxon with a long name, reportedly close to the origin of the Ceratopsia, but I need data.

Barrett PM, Butler RJ and Knoll F 2005. Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China. Journal of Vertebrate Paleontology 25:823-834.
Currie PJ and Padian K 1997. Encyclopedia if Dinosaurs. Academic Press.
Dodson P. 1990. Marginocephalia. Pp. 562-563 in The Dinosauria (Weishampel DB, Dodson P and Osmólska H, eds.) University of California Press, Berkeley.
Lambe LM 1902. New genera and species from the Belly River series (Mid-Cretaceous). Contributions to Canadian Paleontology. Geological Survey of Canada 3:25-81.
Lambe LM 1918. The Cretaceous genus Stegoceras, typifying a new family referred provisionally to the Stegosauria. Transactions of the Royal Society of Canada. 12(4):23-36. Peng G-Z 1990. New small ornithopod (Agilisaurus louderbacki gen. et sp. nov.) from Zigong, China. Newsletter of the Zigong Dinosaur Museum 2: 19–27.
Peng G-Z 1992. Jurassic ornithopod Agilisaurus louderbacki (Ornithopoda: Fabrosauridae) from Zigong, Sichuan, China. Translated by Will Downs. Vertebrata Palasiatica 30: 39-51.
Sullivan RM 2003. Revision of the dinosaur Stegoceras Lambe (Ornithischia, Pachycephalosauridae). Journal of Vertebrate Paleontology 23 (1): 181–207.
Xu X, Forster CA, Clark JM and Mo J 2006. A basal ceratopsian with transitional features from the Late Jurassic of northwestern China. Proceedings of the Royal Society B: Biological Sciences 273: 2135–40. doi:10.1098/rspb.2006.3566. PMC 1635516. PMID 16901832.


New insights into the ornithopod manus

like Edmontosaurus, and their kin are the ornithopod ornithischian dinosaurs, a clade I have been ignoring until now. Wikipedia reports, “[they] started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American landscape.” 

Dryosaurus, Camptosaurus, Iguanodon and Edmontosaurus are genera within this clade and each has an interesting manus (Fig. 1). When one works in phylogenetic analysis it is imperative to compare homologous digits (apples to apples). In ornithopods, those homologies appear to be masked and perhaps misinterpreted by the appearances of new phalanges and the disappearances of old phalanges. Putting them all in one image (Fig.1) clarifies all issues (even without traveling to visit the fossils firsthand!). Hopefully the data are accurate to start with.

This all started with a phylogenetic analysis
that appeared to indicate that Edmontosaurus had a manual digit 1 with an extra digit that made it look like manual digit 2. Comparisons to other ornithopods ensued. A quick look through the Internet brought B. Switek’s article (see below) to the fore.

Figure 1. Ornithopod manus. Here the hands of Dryosaurus, Camptosaurus, Iguanodon and Edmontosaurus are compared. Note the turquoise metatarsal homologies and the digit identification based on that.

Figure 1. Ornithopod manus. Here the hands of Dryosaurus, Camptosaurus, Iguanodon and Edmontosaurus are compared. Note the turquoise metatarsal homologies and the digit identifications based on that.

Science writer Brian Switek 
writing for Smithsonian.com reports,

  1. “…the great herbivore Iguanodon had prominent thumb spikes.
  2. “The peculiar false thumb of Iguanodon was originally thought to set into the dinosaur’s nose.”
  3. “But why should Iguanodon have a hand spike? “
  4. “Though my own suggestion is not any better than those I have been disappointed by, I wonder if the Iguanodon spike is a Mesozoic equivalent of another false thumb seen among animals today—the enlarged wrist bones of red and giant pandas…  the Iguanodon spike was rigid.” Unfortunately that’s as far as journalist Switek has allowed himself to go, rather than proposing the homologies and comparisons demonstrated here.

Giving credit where credit is due,
Switek may be the first to suggest the spike was not a digit. I don’t know and was not able to find out the history of the spike. Given the text from his blogpost, you can see Switek’s choice of words actually evolves from “thumb spikes” to “false thumb” to “hand spike” to “enlarged wrist bone”. Like Brian, I also lack a PhD, but that doesn’t stop us from making contributions. If I’m duplicating earlier academic efforts, please let me know so credit can be given.

Here we’ll show
that the spike is indeed a wrist element… that digit 1 in Iguanodon and related taxa have one more phalanx, making it look like digit 2.

We’ll start with
the right manus of Dryosaurus, a basal ornithopod (at least in the large reptile tree it is, where only one other ornithopod, Edmontosaurus, is currently represented). During the course of this, I want you to focus on the the homologies of metatarsals 2 and 3 (colored in turquoise). These, I think, will guide us to correct interpretations of the other elements of the various ornithopod manus.

Now back to the manus of Dryosaurus:

  1. Data comes form loose bones in a photo formed in the shape of a hand, not an in-situ articulated hand. Thus I do not know the identification or placement of the carpals
  2. Five metatarsals are present.
  3. Mt3 is the longest. Slightly shorter is mt2.
  4. Phalangeal formula is 2-3-4-3-2, but digit 1 does not appear to be tipped with a sharp ungual. Is it missing? If so, that adds a phalanx to the formula 3-3-4-3-2.
  5. Digit 3 is the longest. Slightly shorter is digit 2.
  6. Unguals are lost in digits 4 and 5.

The manus of Camptosaurus

  1. Is reduced (stumpy) by comparison to Dryosaurus
  2. Mt 1 is a disk. M1.1 is a disk
  3. M3.2 appears to fuse with m3.3
  4. m4.3 and m5.2 are lost
  5. The new phalangeal formula is 2-3-3-2-1

The manus of Iguanodon

  1. is more robust and highly modified by comparison to Dryosaurus
  2. Two wrist elements fill the wrist. Two others extend medially.
  3. Digit 1 is longer and now sports an ungual
  4. Ungual 1 is not sharp
  5. Ungual 2 is a round hoof
  6. Ungual 3 (m3.4) is lost along with m3.3
  7. Mt4 is shorter. Two tiny phalanges are added.
  8. Digit 5 is absent.
  9. The new phalangeal formula is 3-3-2-4-0

The manus of Edmontosaurus 

  1. is long and gracile by comparison to Dryosaurus.
  2. Again, digit 1 has 3 phalanges, matching digits 2–4.
  3. Digit 4 is a vestige
  4. Mt 5 is again absent
  5. As in Iguanodon, ungual 1 is not sharp and ungual 2 is a hoof
  6. The new phalangeal formula is 3-3-3-3-0.

Always interesting to 
uncover little paradigm busters like these. Now back to phylogenetic analysis…

Do ceratopsid juveniles (phylogenetically) nest together?

The discovery of a second juvenile ceratopsid
(Currie et al. 2016) raised an interesting point: “In phylogenetic analysis, if all characters are coded as seen, the two juvenile ceratopsids (a partial Triceratops skull and the UALVP 52613 juvenile, Fig. 1) nest together. However, when size or age dependent characters are [not scored], the new juvenile (Chasmosaurus) specimen groups with other adult Chasmosaurus specimens.”

Figure 1. Chasmosaurus juvenile UALVP 52613 specimen.

Figure 1. Chasmosaurus juvenile UALVP 52613 specimen lacking forelimbs due to  taphoniomic loss down a nearby sinkhole.

So, does phylogenetic analysis fail us?
The new UALVP juvenile was recognized/identified as being closer to Chasmosaurus, just as the juvenile Triceratops was recognized as being closer to Triceratops, both on the basis of character traits and prior to analysis. But the Currie et al. unedited analysis takes us in another direction…

From the introduction
“The specimen comprises a nearly complete skeleton lying on its left side, lacking only the front limbs and girdle, which were lost many years ago into a large sinkhole….”

“The juvenile nature of this specimen is based on several lines of reasoning. At approximately 1.5 min total length, it is the smallest articulated ceratopsid skeleton that has ever been recovered. Immature bone textures on cranial bones (Brown et al., 2009), open neurocentral sutures throughout most of the vertebral column, incomplete fusion of sacral vertebrae, lack of fusion between caudal ribs and vertebrae, poorly formed articulations between limb bones, and many other characters confirm that this is an immature ceratopsid….”

“Of all the chasmosaurines from Dinosaur Park, it is most similar to Chasmosaurus belli and C. russelli.”

This interpretation
was made by expert and experienced assessment. The question is, why would the unedited Currie et al. analysis separate the juveniles from the adults and nest the juveniles together? They’re not exactly tadpoles or caterpillars, but they do change somewhat during maturation, following basic archosauromorph (including synapsid/mammal) growth strategies, that lepidosauromorphs (including pterosaurs) are less likely to follow.

When an adult Chasmosaurus
and the juvenile Chasmosaurus are added to the large reptile tree, using a character list NOT specific to ceratoposids, the juveniles nest with their respective adults, not with each other. And this happens despite the very few bones that represent the juvenile Triceratops (posterior face and shield only). Notably there are no other competing ceratopsid candidates in the present taxon list. All data was gleaned from online images. The adult data may be  represented by chimaera mounts and chimaera drawings. If the Currie et al analysis was restricted to just an adult and juvenile Triceratops and just an adult and juvenile Chasmosaurus, would adults nest with juveniles as they do in the large reptile tree? We don’t know because that test was not run.

Here’s how the large reptile tree divides
the Chasmosaurus adult and juvenile from the Triceratops adult and juvenile (posterior skull traits only). Please feel free to provide better data or more precise readings for any of these interpretations. Some were difficult to figure from available sources. At present I do not include traits for parietal fontanelles or horn lengths, which are the easiest two traits that most commonly separate Chasmosaurus from Triceratops and are reflected in their juveniles.

  1. skull table: C: depressed terrace, medial and lateral crests; T: convex
  2. snout in dorsal view: C: not constricted; T: constricted
  3. orbit positon: C: postorbital > preorbital; T: subequal
  4. lateral rostral shape: C: convex, smooth curve; T: double convex
  5. nasals/frontals: C: nasals >; T: subequal
  6. antorbital fenestra: C: absent; T: without mx fossa
  7. orbit/upper temporal fenestra: C: orbit not > T: orbit >
  8. orbit position/skull: C: anterior half of skull; T: not
  9. orbit shape: C: round to square: T: taller than wide
  10. upper temporal fenestrae: C: not closed or slit-like; T: closed or slit-like
  11. frontal shape: C: not wider posteriorly; T: wider posteriorly
  12. frontal shape 2: C: without posterior processes; T: with posterior processes
  13. posterior rim of parietal: C: transverse; T: anteriorly oriented or curved.
  14. parietal skull table: C: forms a sagittal crest: T: broad
  15. squamosal descent: C: mid level; T: ventral skull (ventral maxilla)
  16. skull roof fusion: C: parietal fusion only; T: frontal fusion and parietal fusion
  17. jaw joint orientation: C: descends from ventral mx; T: in line with ventral mx, after jugal arch.
  18. last maxillary tooth: C: posterior orbit; T: mid orbit
  19. mandible ventrally: C: 2-tier convex; T: straight
  20. 2nd sacral rib: C: not: T: double wide laterally
  21. manus/pes: C: subequal: T: manus smaller
  22. ilium: C: posterior process >; T: not
  23. metatarsal 1:4 ratio: C: 1 not > than half: 4 T: 1> half of 4
  24. metatarsals 2-4: C: < than half the tibia; T: not
  25. pedal 3.1 vs p2.1: C: not > T: 3.1>
  26. metatarsals 2 and 3: C: aligns with mt1; T: aligns with pedal 1.1
  27. pedal 4 length: C: subequal to mt 4; T: > mt4
  28. pedal digit 3 vs 4: C: 4 narrower than 3; T: 4 is not narrower

Shifting the juvenile Triceratops
to the juvenile Chasmosaurus adds 12 steps. Doing the opposite adds 21 steps. Bootstrap scores are over 99-100 for the three nodes represented by the four taxa. I have not reviewed the scores or data in the Currie et al study, which obviously adds more ceratopsid traits.

Added < 24 hours after original publication Below is a new reconstruction of the Triceratops juvenile based on text measurements and an adult skull compared to the original reconstruction that does not appear to have correctly scaled the mandible to the skull elements.

Figure 4. A new reconstruction of the Triceratops juvenile with the mandible and squamosal scaled to text measurements and shaped to adult elements compared to the original (Goodwin et al.) reconstruction which appears to have shortened the mandible.

Figure 4. A new reconstruction of the Triceratops juvenile with the mandible and squamosal scaled to text measurements and shaped to adult elements compared to the original (Goodwin et al.) reconstruction which appears to have shortened the mandible.

A YouTube video, Dinosaurs Decoded, shows Mark Goodwin reassembling the juvenile Triceratops skull. Click here to watch.


Short notes for readers and critics
“Criticism of a writer is absolutely inevitable.” — Malcolm Gladwell.
Gladwell is one of the most respected and best-selling authors in current decades. Nevertheless, this interview on YouTube quotes several critics, many with scathing barbs. So, this give and take between writers and their critics is universal and ‘inevitable.’

On the other hand,
in Science, one either can or cannot duplicate experiments and observations. It should be cut and dried, but with errors and egos on both sides, it rarely is. Even so, most people think it is better to try/experiment with/refute alternate hypotheses. Aaaaaat least that’s the editorial policy at ReptileEvolution.com where occasional lack of talent and insight is sometimes overcome by tenacity, huge blocks of data and the ability to update online blunders.

Currie PJ,  Holmes RB, Ryan MJ and Coy C. 2016. A juvenile chasmosaurine ceratopsid (Dinosauria, Ornithischia) from the Dinosaur Park Formation, Alberta, Canada. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1048348.