Another look at Yutyrannus

Figure 1. Comparing the skulls of Eutyrannus (center) to Allosaurus (above) and Tyrannosaurus (below). Which one appears to share more traits with Yutyrannus? See text for details. The pink portion of the nasal appears to be a lateral crest, as in Allosaurus. Note the central frontal horn. It is hollow, like that of Majungasaurus.

Figure 1. Comparing the skulls of Eutyrannus (center) to Allosaurus (above) and Tyrannosaurus (below). Which one appears to share more traits with Yutyrannus? See text for details. The pink portion of the nasal appears to be a lateral crest, as in Allosaurus. Note the central frontal horn. It is hollow, like that of Majungasaurus.

So, the theropod community
is not happy with the large reptile tree nesting of Yutyrannus with Allosaurus (Figs. 1, 2) and the nesting of Microraptor with Compsognathus (see tomorrow).

I don’t blame them.
A larger matrix with more taxa and more characters specific to theropods (Cau et al. 2015) nests these provisional sisters elsewhere — Microraptor with Velociraptor and Yutyrannus with Tyrannosaurus. Shifting Microraptor next to Velociraptor in the large reptile tree adds 30 steps. Shifting Yutyrannus to T-rex adds 25.

The large theropods
under consideration (Fig. 1) all have a robust skull and share a common ancestor, a sister to Coelophysis in the Late Triassic. Each of the three candidates has prominent lacrimal horns (more prominent in A and Y), an elevated naris (larger in A and Y) and a deep angled jugal (PO process more gracile in A and Y). The nasals also produce lateral crests in A and Y, but crushed into the parasagittal plane in Y.

Note
I have replaced the old skull of Yutyrannus based on the original published drawing with a DGS tracing (Fig. 1) that appears to be more accurate as it replaces certain broken pieces to their invivo positions. The changes did not affect the earlier tree topology.

Yutyrannus/Allosaurus traits
Here following traits scored Yutyrannus with Allosaurus opposed to T-rex.

  1. A and Y share a horizontal premaxilla ventral rim. In T it rises anteriorly.
  2. A and Y share a vertical quadratojugal that interlocks with the squamosal. The quadratojugal of T is hourglass-shaped.
  3. A and Y share a shallow angled posterior dentary. The posterior dentary of T is almost vertical.
  4. A and Y share a ventral naris composed of equal parts premaxilla and nasal. In T the premaxilla extends the majority of the rim.
  5. In A and Y the skull is less than half the length of the presacral column. In T the skull is not less than this length.
  6. In A and Y the nasal is widest at mid length. Not so in T.
  7. In A and Y the lacrimal was deeper than the maxilla. Not so in T.
  8. In A and Y the frontals lack posterior processes. Not so in T.
  9. In A and Y the coronoid process is absent. It is low in T.
  10. In A and Y cervical centra are longer than tall. Not so in T.
  11. In A and Y the cervicals do not decrease cranially. Not so in T.
  12. In A and Y the sacrals are not fused to the ilia. Fused in T.
  13. In A and Yh the second caudal transverse processes are not > centrum width. > in T.
  14. In A and Y a mineralized sternum is absent. Present in T.
  15. In A and Y mc2-3 align with m1.1 They do not align with that joint in T.
  16. In A and Y the ilium anterior process is not > the acetabulum length. It is > in T.
Figure 2. Yutyrannus (middle) compared to Allosaurus (above) and Tyrannosaurus (below). Not to scale. Which one appears to share more traits with Yutyrannus?

Figure 2. Yutyrannus (middle) compared to Allosaurus (above) and Tyrannosaurus (below). Not to scale. Which one appears to share more traits with Yutyrannus?

Also note
the large three-fingered hand in Y (relatively larger than in A, the lack of a pinched metatarsal 2 in Y and a long narrow H-shaped palatine in A and Y, not in T.

Of course 
there is also a list of traits that link Allosaurus with T-rex to the exclusion of Yutyrannus. That’s par for any phylogenetic analysis.

References
Madsen JH Jr. 1993 [1976]. Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey.
Marsh OC 1877. Notice of new dinosaurian reptiles from the Jurassic formation. American Journal of Science and Arts 14: 514–516.
Osborn HF 1905. Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the AMNH (New York City: American Museum of Natural History) 21 (14): 259–265′
Xu X, Wang K, Zhang K, Ma Q, Xing L, Sullivan C, Hu D, Cheng S, Wang S et al. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of China. Nature 484 (7392): 92–95. doi:10.1038/nature10906.  PDF here.

wiki/Yutyrannus
wiki/Allosaurus
wiki/Tyrannosaurus

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A new hypothesis on bat ancestry: seems odd…

Halliday, Upchurch and Goswami (2015)
report they have resolved the relationships of Paleocene placental mammals. That includes bats, of course (subset of their cladogram in Fig. 1).

From their abstract “the affinities of most Paleocene mammals have remained unresolved, despite significant advances in understanding the relationships of the extant orders, hindering efforts to reconstruct robustly the origin and early evolution of placental  mammals. Here we present the largest cladistic analysis of Paleocene placentals to date, from a data matrix including 177 taxa (130 of which are Palaeogene) and 680 morphological characters.”

The ancestry of bats
has been a traditional problem in paleontology. Pterosaur Heresies resolved that to a certain extent here and here. Halliday et al. put forth a new and odd sister taxon, Apatemys (Fig. 2), a small chisel-toothed mammal. Unfortunately the only time Apatemys is mentioned in the text is in the cladogram figure.

Figure 1. A subset of the Halliday et al. 2015 tree attempting to resolve relationships of placental mammals. Here the proximal outgroup for three bats is Apatemys (figure 2).

Figure 1. A subset of the Halliday et al. 2015 tree attempting to resolve relationships of placental mammals. Here the proximal outgroup for three bats is Apatemys (figure 2).

As readers may recall, 
the large reptile tree nested bats with the extinct arboreal carnivores, Vulpavus and Chriacus (Fig. 3) and the small extant mammal Ptilocercus, which we looked at here. In the Halliday et al. tree, Vulpavus nests on a nearby busy branch. Chriacus nests much farther away. Ptilocercus nests as a very basal mammal with Plesiadapis, Notharctus and other primates, far from Tupaia, which nests with Cynocephalus (just the opposite of what the large reptile tree recovered, which aligned Tupaia with rabbits and Ptilocercus with flying lemurs like Cynocephalus.

Figure 2. Apatemys nests as a proximal sister to bats in the Halliday et al. tree. But it shares very few traits with bats. Note the very odd dentition.

Figure 2. Apatemys nests as a proximal sister to bats in the Halliday et al. tree. But it shares very few traits with bats. Note the very odd dentition that no bat shares. This specimen nested with Tupaia, Plesiadapis and other insectivores.

A more generalized and bat-like dentition
is found in Chriacus  (Fig. 3). Unfortunately the fossils are few in the ancestry of bats. We have to work with what we have.

Figure 1. Hypothetical bat ancestors arising from a sister to Chriacus, which may be a large late survivor of a smaller common ancestor.

Figure 1. Hypothetical bat ancestors arising from a sister to Chriacus, which may be a large late survivor of a smaller common ancestor.

The next most proximal outgroups to bats
in the Halliday et al. cladogram include the digging taeniodont Onychodectes and the basal pangolin Escavadodon (Fig. 1, 4). Again, these are all much more derived than a sister to bats needs to be. They are not at all ‘bat-like’. Not sure why the Halliday team arrived at such an odd nesting. It doesn’t appear to make sense. I don’t see any gradual accumulation of derived traits leading up to bats here.

Figure 4. Onychodectes and Escavadodon nest as penultimate outgroups to bats in the Halliday et al. tree, but they really should have nested much further away.

Figure 4. Onychodectes and Escavadodon nest as penultimate outgroups to bats in the Halliday et al. tree, but they really should have nested much further away. Do you agree?

On the other hand
Ptiilocercus (Fig. 5) is still the best example of what a bat ancestor must have looked like, as we examined previously here, here and here.

Figure 4. Ptilocercus, Icaronycteris and a hypothetical transitional taxon based on the ontogenetically immature wing of the embryo Myotis. If you're going to evolve wings it looks like you have to stop using them as hands early on. Note in the bat embryo there is little indication of inter-metacarpal muscle. That area looks identical to the web.

Figure 5. Ptilocercus, Icaronycteris and a hypothetical transitional taxon based on the ontogenetically immature wing of the embryo Myotis. If you’re going to evolve wings it looks like you have to stop using them as hands early on. Note in the bat embryo there is little indication of inter-metacarpal muscle. That area looks identical to the web.

Ptilocercus is the right size,
the right niche, and it has lots of bat-like traits, like that rotating wrist, flat ribs and that high floating scapula.

References
Halliday TJD, Upchurch P and Goswami A 2015. Resolving the relationships of Palaeocene placental mammals. Biological Reviews first published Dec 21, 2015.

 

The Compsognathus-Tyrannosaurus clade to scale

There has been a recent rise in interest
in the new nestings of the theropods recovered here, here, here and here. The present post provides a summary of images and traits from the large reptile tree (Fig. 1).

Figure 1. Latest cladogram of the Theropoda, including the Compsognathus-Tyrannosaurus clade.

Figure 1. Latest cladogram of the Theropoda, including the Compsognathus-Tyrannosaurus clade.

The large reptile tree 
nests Compsognathus at the base of a clade that includes Microraptor, Sinornithosaurus, Tianyuraptor, Zhenyuanlong and Tyrannosaurus (Fig. 2). The middle taxa (above) are traditionally considered dromaeosaurs and indeed nest with dromaeosaurs in very large cladograms focused on theropods (Cau et al. 2015).

Figure 2. Taxa in the Compsognathus/Tyrannosaurus clade, a subset of the large reptile tree to scale. Also included are Microraptor, Sinornithosaurus, Dilong and Zhenyuanlong.

Figure 2. Taxa in the Compsognathus/Tyrannosaurus clade, a subset of the large reptile tree to scale. Also included are Microraptor, Sinornithosaurus, Tianyuraptor and Zhenyuanlong.

Unfortunately
the large reptile tree does not confirm many of the nestings recovered by the Cau et al. study, which employed many more taxa and characters specific to theropods (to their credit), not generalized to all reptiles. They also did not create reconstructions of included taxa, so the researcher has to look at their character scores to confirm validity. Sometimes a picture streamlines difficult tasks like this. Cau eta al updated the matrix of Lee et al. 2014 (which included two of the former authors). So they didn’t have to examine each taxon, nor photographs or drawings of each and every taxon. Likely they accepted most of the data as correct — which it indeed may be. But in Science, remember, EVERYTHING is provisional, even what you read and see here.

The Cau et al. study
nested Archaeopteryx (as only one taxon) basal to Xiaotingia, Rahonavis and Balaur. By contrast the large reptile tree nests these taxa basal to six specimens of Archaeopteryx, each basal to distinct derived avian clades

Distinct from other theropods
(in the large reptile tree), this clade (Fig. 2) shares the following traits:

  1. skull not shorter than cervicals
  2. lateral rostral shape convex, smooth curve (reversed in T)
  3. frontals separated from upper temporal fenestrae (reversed in Z and T)
  4. procumbent premaxillary teeth (reversed in S and T)
  5. ventral mandible convex anteriorly, concave posteriorly (reversed in T)

The Tianyuraptor/Zhenyuanlong/Tyrannosaurus clade
shares the following traits:

  1. snout occiput length not less than half the presacral length
  2. dorsal nasal shape triangular, wider anteriorly
  3. ventral premaxilla tilted up
  4. orbit not larger than antorbital fenestra
  5. parietal skull table strongly constricted
  6. quadratojugal hourglass shaped
  7. posterior mandible deeper anteriorly
  8. midcervical centrum taller than long
  9. cervical size decreases cranially
  10. cervicals parallelogram shaped in lateral view
  11. anterior chevrons parallel to centra (reversed in T)
  12. pedal 4 length sub equal to mt4

Of course
these and many other traits are shared with other taxa by convergence. As always, it is the suite of traits that nests taxa.

Figure 3. Bird origins. Apparently the four-winged micro raptors were no in the direct line of living birds.

Figure 3. Bird origins. Apparently the four-winged microraptors were no in the direct line of living birds.

 

Figure 4. Sinornithosaurus (holotype) pelvis. Note the pubis is oriented ventrally, then curves posteriorly.

Figure 4. Sinornithosaurus (holotype) pelvis. Note the pubis is oriented ventrally, then curves or angles posteriorly.

The Sinornithosaurus pelvis
is indeed similar to that of Velociraptor pelvis (Fig. 3). Similar, yes, but also distinct in morphology.

I’m just reporting results
and they appear (Fig. 2) that make a certain amount of sense. There’s no reason to criticize a worker for methodology. If specific mistakes are found, please alert the author.

Let’s find common ground and figure this out.

References
Cau et al. 2015. The phylogenetic affinities of the bizarre Late Cretaceous Romanian theropod Balaur bondoc (Dinosauria, Maniraptora): dromaeosaurid or flightless bird? PeerJ 3:e1032; DOI 10.7717/peerj.1032

Lee MSY, Cau A, Naish D, Dyke GJ. 2014. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds. Science 345(6196):562–566. DOI 10.1126/science.1252243.

Guanlong and Dilong: basal allosaurs, not basal tyrannosaurs

I thought more taxa
would help the present shifting of taxa from their original designations, seen here, here and here.

Figure 1. Guanlong reconstructed by moving elements tracing Xu et al. 2006.

Figure 1. Guanlong reconstructed by moving elements tracing Xu et al. 2006. The robust foot and small skull are notable.

Giuanlong wucaii (Xu et al. 2006, Late Jurassic, China, 3m long) was originally considered a basal tyrannosauroid. An adult (IVPP V14531) and a more complete juvenile (IVPP V14532) are known. The adult had an elaborate medial nasal head crest. The juvenile had  a smaller crest restricted to the anterior.

Figure 1. Theropod cladogram. With the addition of Guanlong and the identification of prior errors, the nesting of the microraptors separates from the tyrannosaurs, but Guanlong nests with Sinocalliopteryx, Allosaurus and Yutyrannus, not tyrannosaurs.

Figure 2. Theropod cladogram. Guanlong nests with two other putative tyrannosaurs, Dilong and Yutyrannus, along with feathered Sinocalliopteryx and Allosaurus.

Here Guanlong nests
in the large reptile tree (Fig. 1) at the base of the Allosaurus clade, not the T-rex clade. But note the Allosaurus clade nests at the base of the T-rex clade. Remember I’m using generalized traits to lump and separate my taxa, not traits specific to theropods.

According to Xu et al. 2006
traits Guanlong shares with tyrannosauroids largely exclusive of other theropods include:

  1. large foramina on the lateral surface of the premaxilla
  2. tall premaxillary body
  3. fused nasals
  4. a large frontal contribution to the supratemporal fossa
  5. a pneumatic jugal foramen in the posterior rim of the antorbital fossa
  6. a deep basisphenoidal sinus with large foramina
  7. a subcondylar recess on the basisphenoid
  8. the supraoccipital excluded from the foramen magnum
  9. the short retroarticular process
  10. the relatively small, U-shaped premaxillary teeth that are arranged in a row more transversely than anteroposteriorly oriented
  11. and labio-lingually thick maxillary and dentary teeth
  12. Striking tyrannosauroid pelvic features include an ilium subequal to femoral length, a distinctive dorsal concavity on the pre-acetabular process, a supracetabular crest that is straight in dorsal view, a prominent median vertical crest on the lateral surface of the ilium, a concave anterior margin of the pubic peduncle, a pubic tubercle close to the dorsal part of the pubic shaft, an extremely large pubic boot (55% of pubic length), and a thin sheet of bone extending from the obturator process down the ischial shaft

None of these are character traits listed in the large reptile tree. The authors note, “Guanlong represents a specialized lineage in the early evolution of tyrannosauroids.”

Figure 2. The CM 31374 specimen of Coelophysis.

Figure 3. The CM 31374 specimen of Coelophysis. The long snout becomes progressively shortened in the Guanlong/Dilong clade.

The unusually long snout of Guanlong
might appears to be elongated in order to support a larger crest. The authors note, “Cranial horns, bosses and crests are present in many non-avian theropods and are best exemplified by Dilophosaurus, Monolophosaurus and oviraptorids, among others.” However, Guanlong is also derived from a sister to Coelophysis, which also had a longer rostrum and similar proportions.

Figure 4. Dilong paradoxus. Images from Xu et al. 2004. Colors added.

Figure 4. Dilong paradoxus. Images from Xu et al. 2004. Colors added.

Dilong paradoxus (Xu et al., 2004 TNP01109) Early Cretaceous ~125 mya, 2.75 m in length, was also originally considered a basal tyrannosauroid. In the large reptile tree (Fig. 2) it is derived from a sister to Guanlong at the base of the Allosaurus/Sinocalliopteryx clade. Dilong was larger than Guanlong and covered with feathers or protofeathers. Here the snout is shorter still.

None of these taxa 
are known to have stiff wing feathers as seen in the tyrannosaurs, like Zhenyuanlong, and later clades leading to birds.

References
Xu X, Clark JM, Forster CA, Norell MA, Erickson GM, Eberth DA, Jia C and Zhao Q 2006. A basal tyrannosauroid dinosaur from the Late Jurassic of China” (PDF). Nature 439 (7077): 715–718.
Xu X, Norell MA, Kuang X, Wang X, Zhao Q, Jia C 2004. Basal tyrannosauroids from China and evidence for protofeathers in tyrannosauroid (PDF). Nature 431 7009: 680–684.

wiki/Dilong_paradoxus

Yutyrannus: NOT a tyrannosaur!

Modified December 27, 2015 and December 29, 2015 with the addition of a reconstruction of Yutyrannus and a theropod cladogram. 

Okay, this is getting ridiculous. 
I stayed away from dinosaurs, and theropod dinosaurs because I thought many others had covered them so thoroughly. Evidently, not so. Lots of theropods are getting nested at new nodes lately.

Figure 1. Yutyrannus reconstructed.

Figure 1. Yutyrannus reconstructed.

Yutyrannus is famous
for being a giant feathered theropod, several times larger than the next largest contender. Yutyrannus huali  (Xu et al. 2012 ZCDM V5000 Zhucheng Dinosaur Museum, Shandong, Lower Cretaceous Yixian Formation) was originally considered a tyrannosauroid theropod.

Famous for feathers
Xu et al. report, “Most significantly, Y. huali bears long filamentous feathers, thus providing direct evidence for the pres- ence of extensively feathered gigantic dinosaurs and offering new insights into early feather evolution.”

Figure 1. Yutyrannus nests not with tyrannosaurs but with allosaurs. And it is feathered.

Figure 2. Yutyrannus nests not with tyrannosaurs but with allosaurs. And it is feathered. Click to enlarge. Femoral length = 85 cm in the adult. That’s a pnenmatic midline crest created by the nasals. The postfrontal and postorbital are distinctly colored here but fused in the specimen.

 

I’ve added a new image (Fig. 2b) based on a DGS tracing of a photograph of the specimen ZCDM V5000 that is slightly different than the original drawing (Fig. 2a).

Figure 2b. DGS tracing of one of the specimens of Yutyrannus. Figure 1 has been modified to the new skull.

Figure 2b. DGS tracing of one of the specimens of Yutyrannus. Figure 1 has been modified to the new skull.

Phylogenetic analysis
Xu et al. report, “Phylogenetic analyses using two different theropod matrices place this taxon among basal tyrannosauroids, but relatively close to the Tyrannosauridae.” 

Figure 1. Theropod cladogram. With the addition of Guanlong and the identification of prior errors, the nesting of the microraptors separates from the tyrannosaurs, but Guanlong nests with Sinocalliopteryx, Allosaurus and Yutyrannus, not tyrannosaurs.

Figure 3. Theropod cladogram. With the addition of Guanlong and the identification of prior errors, the nesting of the microraptors separates from the tyrannosaurs, but Guanlong nests with Sinocalliopteryx, Allosaurus and Yutyrannus, not tyrannosaurs.

Unfortunately
the large reptile tree (now 620 taxa) nests Yutyrannus unambiguously with another giant theropod, Allosaurus. Not sure why we have such a difference here, unless untested basal tyrannosaurs converge strongly with Allosaurus. Or was there an initial bias? Or does Yutyrannus nest with tyrannosaurs when only theropod traits are employed? The large reptile tree uses such generalized traits that it covers every tested taxon from basal tetrapods to humans, turtles, snakes and birds.

Figure 2. Skull of Allosaurus for comparison to Yutyrannus.

Figure 4. Skull of Allosaurus for comparison to Yutyrannus.

I can’t believe this the first time
the tyrannosaur relationship of Yutyrannus was not recovered in a phylogenetic analysis. Let me know of any prior studies that recovered a similar nesting so I can give proper credit.

And Merry Christmas everyone…

References
Xu X, Wang K, Zhang K, Ma Q, Xing L, Sullivan C, Hu D, Cheng S, Wang S et al. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of ChinaNature 484 (7392): 92–95. doi:10.1038/nature10906. Get a PDF here.

And now Dave, the Sinornithosaurus, leaves the ‘raptors’

Revised December 27, 2015 with extended scapulae on both the tracing and reconstruction.

Yes, I know it has feathers
And yes, it has a tail stiffened with elongated processes.
And yes, it has long ‘raptor’ fingers.
And yes, it could have had a posteriorly-oriented pubis.
And it had relatively shorter hind limbs.

I was really hoping
this one would pull the other micro- aptors back to raptor-ville.

Figure 1. Sinornithosaurus ("Dave", NGMC 91) shown as plate and DGS tracing.

Figure 1. Sinornithosaurus (“Dave”, NGMC 91) shown as plate and DGS tracing.

Even so…
the present (and always provisional) suite of character traits currently attributed to ‘Dave’, the Sinornithosaurus (NGMC 91, Ji et al. 2001) nests it (Fig. 3.) with Microraptor (in the large reptile tree at 619 taxa) which nests with Compsognathus and Tianyuraptor + Zhenyuanlong + Tyrannosaurus. Not Velociraptor.

Figure 2. Reconstruction of Sinornithosaurus based on DGS tracing of figure 1. Note the oddly small scapula and coracoid. Ribs and gastralia were omitted from the lateral view.

Figure 2. Reconstruction of Sinornithosaurus based on DGS tracing of figure 1. Note the oddly small coracoid. Ribs and gastralia were omitted from the lateral view.

You know,
sometimes you just have to go where the data takes you.

Figure 3. Theropod subset of the large reptile tree showing the nesting of Sinornithosaurus.

Figure 3. Theropod subset of the large reptile tree showing the nesting of Sinornithosaurus.

Some interesting things happen
when you play deletion games. For instance, delete the four taxa closest to Sinornithosaurus and there’s a shift in tree topology. T-rex nests between Sinocalliopteryx + Allosaurus and Compsognathus, which nests basal to Sinornithosaurus, and the rest of the tree is the same. The re-insertion of any one of the deleted taxa does not repair the tree other than Tianyuraptor, which alone restores the topology.

And finally, a little about Sinornithosaurus
I note oddly small coracoids here. While the coracoid is elongated, it is also much smaller, probably due to a reduction in flapping capabilities. The so-called ‘killer’ toe claw (#2) is long and gracile, not what you might call robust. Perhaps ideal for perching, but pedal digit 1 is also oddly tiny. The specimen appears to have smaller wing feathers than in Microraptor, it’s provisional ancestor sister. It also has shorter teeth and a down-tipped premaxilla.

References
Ji Q, Norell MA, Gao KQ, Ji S-A and Ren D 2001. The distribution of integumentary structures in a feathered dinosaurs. Nature, 410(6832): 1084-1087.

wiki/Sinornithosaurus

 

Microraptor: not a ‘raptor’??

Earlier
the large reptile tree nested two putative dromaeosaurs with composgnathid/tyrannosaurs, Tianyuraptor and Zhenyuanlong. Today the famous four-wiinged dinosaur/bird Microraptor (Figs. 1, 2) is added to that list, nesting between Compsognathus and Tianyuraptor, all three basal to T-rex.

Figure 1. Microraptor gui (IVPP V 13352) shown in two photos and with DGS tracing of bones and feathers.

Figure 1. Microraptor gui (IVPP V 13352) shown in two photos and with DGS tracing of bones and feathers. Click to enlarge.

This is the specimen
that inspired a PBS Nova special and a race between competing teams of paleontologists to figure out the best usage for the odd foot feathers. The Kansas team led by Dr. Larry Martin produced a sprawling model that went against everything we know di dinosaur hind limbs.

Figure 2. Microraptor gui (IVPP V 13352) reconstructed from tracings in figure 1. There are no surprises here, except a provisional closer relationship with Compsognathus than with Velociraptor. Microraptor has a large pedal claw two, but it is not quite the killing claw seen in droamaeosaurs.

Figure 2. Microraptor gui (IVPP V 13352) reconstructed from tracings in figure 1. There are no surprises here, except a provisional closer relationship with Compsognathus than with Velociraptor. Microraptor has a large pedal claw two, but it is not quite the killing claw seen in droamaeosaurs.

So this makes three former dromaeosaurs
now nesting with long-legged Compsognathus and Tyrannosaurus. Among them, only Microraptor has long arms/wings. Zhenyuanlong has equally substantial feathers. So this adds credulity to the idea that Compsognathus was well feathered. Only Microraptor has a posteriorly directed pubic foot, but see Compsognathus (Fig. 4) for its derivation. This is not a posteriorly directed pubis.

Figure 4. Compsognathus was not preserved with feathers, but with a sister taxon like Microraptor, it might have had substantial feathers.

Figure 4. Compsognathus was not preserved with feathers, but with a sister taxon like Microraptor, it might have had substantial feathers.

Is Microraptor a bird (clade Aves)?
Wikipedia (Evolution of Birds) defined Aves as “all descendants of the most recent common ancestor of a specific modern bird species (such as the house sparrow, Passer domesticus), and either Archaeopteryx, or some prehistoric species closer to Neornithes (to avoid the problems caused by the unclear relationships of Archaeopteryx to other theropods).[ If the latter classification is used then the larger group is termed Avialae. Currently, the relationship between dinosaurs, Archaeopteryx, and modern birds is still under debate.”

Is Microraptor a member of the clade Avialae?
Wikipedia defines the clade Avialae “a clade of dinosaurs containing their only living representatives, the birds. It is usually defined as all theropod dinosaurs more closely related to modern birds (Aves) than to deinonychosaurs, though alternate definitions are occasionally used (see below).” 

So, Microraptor is not a bird. 
In the same light, not all Archaeopteryx specimens are birds, but Wellnhoferia (aka The Solnhofen specimen, Archaeopteryx grandis) apparently is a bird as it nests closest to living birds of all Solnhofen specimens.

Yes
I don’t have a complete list of theropods in the large reptile tree. But this is what the tree recovers at present. If valid, theropods with long feathers on their forelimbs appear earlier than some workers think. And maybe I’m just catching up to the rest of them.

There are other specimens out there referred to Microraptor
and I have not tested them yet. Perhaps one or more are more closely related to Velociraptor. 

Addendum
Here is the skull of the QM V 1002 specimen of Microraptor (Fig. 5, Xing et al. 2013). The two nest together in the large reptile tree, but differ in several traits. They are not conspecific.

Figure 5. The skull of another Microraptor, QM V1002. The two nest together in the large reptile tree.

Figure 5. The skull of another Microraptor, QM V1002, the fish eater. The two nest together in the large reptile tree. I’m a little confused by the occiput. I’ll get back to that later.

References
Xing L, Persons WS, Bell PR, Xu X, Zhang J-P, Miyashita T, Wang F-P and Currie P 2013. Piscivery iin the feathered dinosaur Microraptor. Evolution 67(8):2441-2445.
Xu X, Zhou Z, Wang X, Kuang X, Zhang F, and Du X 2003. Four-winged dinosaurs from China. Nature, 421: 335–340.

wiki/Microraptor