Maniraptora

   Maniraptora is the sister group to Arctometatarsalia and together with it makes up Maniraptoriformes. It has several main groups: the eumaniraptors, includining Dromaeosauridae, or "raptors", the gracile Troodontidae, and Avialae (sometimes the dromies and trudies end up together in analyses, as Deinonychosauria, but other analyses find dromaeosaurids closer to birds, yet others find troodontids closer to birds, and I figure that the only given is that both dromies and trudies wanted to be close to birds when they were hungry); Oviraptorosauria (Caenagnathidae/Elmisauridae and Oviraptoridae); Alvarezsauridae; Therizinosauria; and Avialae. Feathers or protofeathers are known for dromaeosaurids, troodontids, basal oviraptorosaurians, basal therizinosaurians, and avialans (this one is easily verified), suggesting all maniraptorans possessed one or the other. Oviraptorosauria and Therizinosauria are sometimes combined into one group, Oviraptoriformes (informally "Enigmosauria"). What follows would pass for conservative, if I actually knew what I was doing.
    
<--Maniraptora
      |-->Therizinosauria
      `--+-->Alvarezsauridae
           `--+-->Oviraptorosauria
                |  Maniraptora i.s.:
                |  Scansoriopterygidae
                |   |--Epidendrosaurus/Scansoriopteryx 
                |   `--Epidexypteryx
                `--Eumaniraptora
                     |  "Nexus of basal eumaniraptorans"  
                     |-->Dromaeosauridae
                     |-->Troodontidae
                     `--Avialae
                          |--?Archaeopteryx
                          `--A whole bunch of extinct non-classic dinosaurian birds, leading to...
                               `--The modern birds we all know and love, except when they
                                   decorate our motor vehicles and other outdoor objects (as you
                                   can probably guess, birds aren't my strong suit).

Maniraptora i.s.: Scansoriopterygidae: This is the place to go to find weird little things with weird long third fingers, an unusual need, but who am I to ask questions? The scansoriopterygids appear to be some kind of derived maniraptorans, but their relationships have so far proven elusive. Opinions have been coalescing around three assignments: the sister group of Oviraptorosauria, the sister group to Eumaniraptora (which would make them paravians; see below), and basal avialians (and possibly closer to birds than Archaeopteryx).

Epidendrosaurus nighchengensis Zhang, Zhou, Xu, and Wang, 2002 (?Scansoriopteryx) ?MJ-?LJ of China Based on a juvenile (essentially weeks-removed from hatching) specimen, Epidendrosaurus includes unusual features, such as an extremely elongated third finger, which indicate that it could climb trees.
Epidexipteryx hui F. Zhang, Z. Zhou, X. Xu, X. Wang, and Sullivan, 2008 ?MJ-?LJ of China Little Epidexi was a short-tailed short-snouted maniraptoran with long strap or ribbon-like feather things on its stubby tail. It was similar to the scansoriopterygids Epidendrosaurus and Scansoriopteryx, although unfortunately its hands are are one of the few parts of the body that aren't preserved clearly (the scansoriopteygids, of course, having very distinctive hands). 
Scansoriopteryx heilmanni Czerkas and Yuan, 2002 (?Epidendrosaurus) ?MJ-?LJ of China Based on a partial juvenile skeleton including skull and limb elements, Scansoriopteryx appears to be a climbing maniraptoran (probably the same as Epidendrosaurus, but this is not quite nailed down). It had an unusually long third digit of the hand, longer than the other two digits. 

Maniraptora i.s.:  

Taxon or Taxa: Time/Place: Comments:
Bradycneme draculae (N.D.) Harrison and Walker, 1975 early-mid Maastrichtian (LK) of Romania Bradycneme is based on a poorly-preserved distal tibiotarsus (tibia and fused ankle elements), originally thought to belong to an owl. This has some resemblance to corresponding elements in the troodontids, but cannot be classified beyond Maniraptora indeterminate.
Palaeopteryx thomsoni (N.D.) Jensen, 1981 late Kimmeridgian (LJ) of Colorado Based on what was considered to be a bird's remains, this animal turned out to be more a more basal small maniraptoran theropod.
?Shanyangosaurus niupanggouensis Xue, Zhang, and Bi, 1996 mid-late Maastrichtian (LK) of China Shanyangosaurus is an obscure small theropod, based on a large (but unfortunately poorly preserved) portion of the postcranium. This mysterious animal is currently distinguished by the unique form of its cnemial crest (a process on the upper end of the tibia, corresponding roughly to the knee). It seems to be closest to the oviraptorosaurians. It may or may not have possessed uncinate processes, which are like bony horizontal rods projecting from the ribs. These are seen in avians and some classic dinosaurs.
Variraptor mechinorum (N.D.) Le Loeuff and Buffetaut, 1998 late Campanian-early Maastrichtian (LK) of France Originally described as a dromaeosaurid but based on possibly chimeric material, this theropod was described as favoring carrion.
Wyleyia valdensis (N.D.) Harrison and Walker, 1973 Barremian (EK) of England This small theropod is based on part of a humerus (upper arm bone) that was originally described as that of a true bird.
Xinjiangovenator parvus Rauhut and Xu, 2005 ?Valanginian-Albian (EK) of China Based on a partial hindlimb (tibia, fibula, astragalus, and calcaneum) originally referred to Phaedrolosaurus, this animal appears to be some sort of maniraptoran, currently without a more inclusive home. There is a vague possible relationship with Bagaraatan. It has an unusual groove on the fibula.
Yixianosaurus longimanus Xu and Wang, 2003 early Aptian (EK) of China From the Yixian, as its name makes clear, this taxon is based on the forelimbs and shoulders of a maniraptoran with exceedingly long hands, suggesting derived tree-climbing abilities. Some feathers are also preserved.
Zhongornis haoae Gao C., Chiappe, Meng, O'Connor, Wang X. R., Cheng X., and Liu J. Y., 2008 early Aptian (EK) of China Zhongornis, known from a largely complete but poorly preserved skeleton of a juvenile, was originally described as a basal bird. More recent analysis suggests that it was a more basal maniraptoran.

Eumaniraptora i.s.: Eumaniraptorans get all the press. The taxon Paraves is roughly equivalent to Eumaniraptora; Eumaniraptora is the least inclusive group including Deinonychus and birds (a node-based group), whereas Paraves is all theropods closer to birds than to Oviraptor (a stem-based group). Thus, as arranged here, there could be non-eumaniraptoran paravians, but not the other way around. If troodontids were basal to the group Deinonychus+birds, there would be a substantial group of non-eumaniraptoran paravians, but for now and the purposes of this page, Eumaniraptora and Paraves are functionally the same. There is also the possibility that troodontids were closer to birds than dromaeosaurids, but this wouldn't cause the troodontids to become non-eumaniraptoran paravians.
    Eumaniraptora i.s. is reserved for critters that might be dromaeosaurids or troodontids, differing from the nexus below, which includes things that might be avialans as well (and which also are better known; the taxa in the following table are represented by a grand total of some teeth, a shoulder girdle, a femur, and a foot, and languish in obscurity).

Taxon or Taxa: Time/Place: Comments:
Hulsanpes perlei Osmolska, 1982 ?mid Campanian (LK) of Mongolia Based on foot bones pertaining to a juvenile individual, Hulsanpes may be a juvenile of its own taxon, another classic theropod, or a bird. While Dromaeosauridae was the traditional destination, Troodontidae may be more likely.
"Koreanosaurus koreanensis" (N.N.) Kim, 1979 Aptian-early Albian (EK) of South Korea Based on a femur, this animal has been called at different times a tyrannosaurid, hypsilophodontid, and dromaeosaurid (even the same as Deinonychus). Its reported possession of a fourth trochanter at least means it can't be regular old Deinonychus, but at this point it's still pretty mysterious, although apparently close to if not a dromaeosaurid. Whatever it is, it cannot be named Koreanosaurus, as that name was officially used for a basal ornithopod (hypsilophodont; what goes around, comes around, I guess).
"Laelaps": "L." explanatus (N.D.) Cope, 1876 late middle Campanian (LK) of Montana These two tooth taxa are usually assigned to Dromaeosaurus, although there has been a suggestion that they represent troodontids instead. 
"L." laevifrons (N.D.) Cope, 1876
Pneumatoraptor fodori Ősi, Apesteguía, and Kowalewski, 2010 Santonian (LK) of Hungary Pneumatoraptor is based on a paravian left shoulder girdle. Some other miscellaneous bones from the same formation may pertain to it. The name refers to the pneumaticity of the bone.

"Nexus of basal eumaniraptorans": Like the basal coelurosaurians, there are a handful of eumaniraptorans that have had difficulty making up their figurative minds about whether they are basal dromaeosaurids, basal troodontids, or basal avialans. Rather than switch them around after every new study, I am collecting them here. In general, these are very similar animals, a meter or less in length, of gracile build with slim skulls and relatively long arms, and are often preserved with feathers. Balaur and Rahonavis, tentatively kept with the dromaeosaurids, may belong here too.

Taxon or Taxa: Time/Place: Comments:
Anchiornis huxleyi Xu X., Zhao Q., Norell, Sullivan, Hone, Erickson, Wang X., Han F., and Guo Y., 2009 Oxfordian (LJ) of China Anchiornis was initially described as a feathered eumaniraptoran of uncertain affinities; at the time, the head wasn't known and neither was the age. We now have both of those details, and it turns out to be from the early Late Jurassic (something of a surprise). It was thought to be a basal troodontid once the head was in hand, which would make it both the earliest named troodontid and one of the oldest feathered dinosaurs. Further work suggests it was closer to Archaeopteryx, but you know how changeable these things get at the base of a lineage. Rather than commit, I stuck it here. It was pretty tiny, estimated as a little over a foot long (the type specimen missing the skull, part of the tail, and the right arm). Its arms were 80% the length of its legs, similar to Archaeopteryx. Lengthy feathers were present on both arms and legs, and there was a crest of feathers on the head. Structural analysis of the feathers indicates that the crest was reddish, the body feathers were dark grey, and the wing feathers (arms and legs) were white with black tips. 
Aurornis xui Godefroit, Cau, Hu D.-Y., Escuillié Wu W., and Dyke, 2013 Oxfordian (MJ) of China Aurornis is based on the skeleton, with feather impressions, of a pheasant-sized animal that's either a very basal avialan or about as close as you can get to being a bird without having to list it as your occupation. It seems to be slightly less derived than Archaeopteryx, but of course once you get into the nexus the distinctions become very fine indeed. It was probably flightless.
Eosinopteryx brevipenna Godefroit, Demuynck, Dyke, Hu, Escuillié, and Claeys, 2013 Oxfordian (LJ) of China Eosinopteryx is known from a skeleton with feather impressions. Large complex feathers appear to have been absent from the tail or legs. The proportions, at least to my eyes, indicate something half-grown or a somewhat awkward-looking species. For example, the eye sockets are large, the snout is short, and the tail is short. It was interpreted as terrestrial, with small and flattened claws, and may be a close relative of the roughly contemporaneous Anchiornis.
Jinfengopteryx elegans Ji, Ji, Lu, You, Chen, Liu, and Liu, 2005 early Aptian (EK) of China Known from most of the skeleton of a single individual, including feather impressions, Jinfengopteryx was described as an archaeopterygid, but others have suggested that it instead is a basal troodontid. This is not a particularly large leap, as a basal troodontid and an Archaeopteryx-grade theropod would be fairly similar; a major difference is the length of the forelimbs, and Jinfengopteryx follows troodontids in having relatively short arms.
Pedopenna daohugouensis Xu and Zhang, 2005 ?MJ-?LJ of China Here's a feathered maniraptoran that's not from the Yixian!  Actually, the most interesting aspects are that it is apparently from the Jurassic, and that it preserves a hindlimb-wing. There's not a whole lot of material, just an articulated right hindlimb from the mid tibia to the toes, with large feather impressions, particularly associated with the metatarsals. It is considered to be an eumaniraptor, but it doesn't fit within the major derived groups included in this grouping. It had an enlarged second claw, and, like most of these early eumaniraptorans, was small, probably less than a meter long.
Xiaotingia zhengi Xu X., You H., Du K., and Han F., 2011 Oxfordian (LJ) of China Xiaotingia gives us another small feathery birdy theropod, helping to fill in more details on what Archaeopteryx-like theropods were doing (we've gotten quite a few small feathery birdy theropods since the mid-1990s, but few that match up well with Archie). It may be a basal dromaeosaurid.

Avialae: From here on out, it's just birds, not classic dinosaurs, so we end our expedition. I assume you're fairly familiar with the characteristics of modern birds, and so will just say early birds differ from modern birds in several important ways: some had teeth, some had bony tails, and some had free fingers that still had claws. These are the major differences.
    Yeah, I gave up the Paulian secondarily-flightless maniraptorans.

Taxon or Taxa: Time/Place: Comments:
?Archaeopteryx:
Meyer, 1861
A. lithographica (type) Meyer, 1861 Tithonian (LJ) of Germany This is the famous "missing link" between birds and classic dinosaurs, and it has held up very well over the years. It is now known from ten skeletons of varying completeness, one of which was considered a pterosaur originally and another of which was originally assigned to Compsognathus. It was about crow-sized in mass, and was probably a decent but not pretty flyer. Specimens of it show both the hyperextendable "sickle-claw" and excellent feather impressions. It is very similar to dromaeosaurids in a number of ways.
It may be that Archie is actually closer to dromaeosaurids and/or troodontids, and birds are descended from more blunt-snouted theropods like the scansoriopterygids.
A new genus has been coined for one of the specimens: Wellnhoferia grandis Elzanowski, 2001 (that's nothing new; practically every specimen has had its own species if not genus at one time or another). The differences given include size and structure of the hindlimbs and tail. While I'm not opposed to there being multiple species of Archaeopteryx, generic separation seems to be a bit much. This is something where time (and more specimens!) will help. A. lithographica seems to be the larger species, and A. siemensii smaller.
A. siemensii Dames, 1897

 

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