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Dcorahead

INTRODUCTION

The coraciiforms of our timeline are a diverse group, even though their number of species is relatively small. Assuming this clade does not turn out to be paraphyletic, Coraciiformes include the pickpeckers(Driostrids), the rollers (Coraciidae), the ground-rollers (Brachypteraciidae) and cuckoo-rollers (Leptosomidae), the todies (Todidae), the motmots (Momotidae), the practically cosmopolitan kingfishers (Alcedinidae), the ancient bee-eaters (Meropidae) of the Old World, the African scimitar-bills (Phoeniculidae) and hoopoes (Upupidae), and the hornbills (Bucerotidae), which could be confused with toucans of either timeline.

Readers are, by this point, probably waiting for a sentence along the lines of: "In Spec, the situation is different." Strangely, however, Spec's coraciiform evolution has been very similar to that of our timeline. Certainly, todies, rollers and hornbills have never evolved in Spec, because their ecological niches are already occupied by jaubs, cacklers and scytherbills; but Spec's p-Coraciiformes contains the nearcrows (Parabrachypteraciidae) and the kingfishers (p-Alcedinidae), which are very similar in shape, diet and distribution to their Home-Earth counterparts.

The order Coraciiformes began, as a group of generalist ground birds very much like the modern Brachypteraciidae (the ground-roller assemblage), and quickly diversified into a number of forms.  Coraciiforms evolved, as most of the earth-familiar birds did, in the southern hemisphere, but quickly spread north.  By the middle Eocene, the coraciiforms were arguably the most diverse of the bird orders, and certainly enjoyed a wide range, with representatives in South America, North America, and Eurasia.

The coraciiforms did not make the march toward world domination unopposed, however.  Nearly all of the avian groups from home-Earth (of which Coraciiformes is one) are descended from a Gondwanan assemblage that escaped the destruction wreaked upon the Northern Hemisphere by the Chicxulub boloid.  On the Specworld, where the extinction never took place, the northern bird lineages were there to meet the coraciiforms.

HISTORY

The Eocene strata of the Messel Shale, in Spec's Germany, clearly demonstrate the battle being waged between the birds of the north and the south.  The most prevalent bird order preserved in Messel is, by far, Twitiaviformes.  These bizarre birds, possibly related to the paleognaths, were probably indigenous to Europe, at the time, although now their greatest diversity is in the Southern Hemisphere.  Following closely behind the twitiavians in species-count are the coraciiforms, while several extinct orders of enantiornithian birds were already loosing ground to the southern invaders.

The competition imposed by the twitiavians greatly changed the direction of coraciiform evolution during the middle Tertiary.  After their upswing in the late Eocene and early Oligocene, Coraciiformes experienced a pronounced depression and went completely extinct in the Old World, but for a few strongholds in Africa and Madagascar.

For much of the remainder of the Tertiary, coraciiforms barely hung on in the Old World with many clades (hornbills, hoopoes, scimitar-bills, and cuckoo rollers, to name a few) going completely extinct or simply failing to evolve.  In the New World, however, the story was different.

The twitiavians have a long history in South America, but for some reason, their penetration of North America has never been very extensive.  It was in North America, then, that the coraciiforms continued to rule with little opposition.  While the Old-world species died out, the American coraciiforms experienced a renaissance of diversity, radiating into many bizarre niches, most notably the piscivorous alcedinids (kingfishers)  and the bizarre, wood-boring dirostrids (pickpeckers).  During the Pliocene and Pleistocene, these clades spread from North America to colonize every continent but Antarctica (there are even alcedinids in twitiaviform-dominated Australia).

Meanwhile, in Africa, the Pliocene saw a new adaptive radiation of Coracii, the primitive branch of Coraciiformes supposedly relegated to obscurity by Twitiaviformes.  Sub-clade Coracii, the most basal branch of the coraciiform tree, suddenly exploded across Africa and Eurasia as Parabrachypteraciidae, or nearcrows.  Today, the generalist/scavenger nearcrows are ubiquitous in Africa, Eurasia, and the Americas, filling the niches that, on Home-Earth, would be occupied by the passerine corvids, the crows.

While the Americas remain center of coraciiform diversity, many of the clade's 500 known species may be found on every continent except for Antarctica. 

DIROSTRIDS (Pickpeckers)

Pickpeckerhead

Fig 1: Head of a typical dirostrid

    Dirostrids, the pickpeckers, are the strangest of the coraciiformes, and arguably the most sucssesful.  These creatures are reletively new additions to their family tree, arising  some time during the Pliocene and quickly spreading from North America to Eurasia, Africa, and (somewhat later) South America. 

The pickpeckers possess a beak structure unique in Spec's birds, although they bear a superficial resemblance to the passerine akiapolaau (Hemignathus wilsoni)  of Home-Earth's Hawaii.  A pickpecker's upper mandible is curved and hook-like, while the lower bill forms a blunt, robust pick, similar to the beak of an RL woodpecker.  Pickpeckers feed by bracing themselves against a vertical tree-trunk will powerful talons (see below) and a stiff, bristly tail.  They then slowly walk about the bark, feeling with their feet for the tell-tale vibrations of a wood-boring insect larva.  Upon locating food, the pickpecker opens its mouth, specialized mandibular joints allowing the bird to yawn impossibly wide, and then drives its lower bill into the wood, shattering bark to expose the hiding food.  Pickpecker skulls are composed of rather spongy bone, and their necks articulate in such a way that their hammering motion is only possible on a single plane, thus avoiding the shearing forces that would pulverize the birds' brains. A pickpecker may hammer at wood at speeds of 15 to 20 kph, stripping the protective bark from above a burrowing grub that the bird may then extract with the aid of its curved, pick-like upper bill.

Another interesting feature of the dirostrids' physiology is their pedal structure.  Pickpecker toes are arranged in a unique 'zygosyndactyl' configuration, with digits one and four fully reversed and opposed to digits two and three, which are fused at the first joint.  Zygosyndacylity is no doubt a product of the kingfishers'  zygodactyl feet evolving in convergence with the syndactyl  feet of the woodpeckers of Home Earth.  The zygosyndactyl arrangement gives a pickpecker a firm hold on its vertical perch, and gives the bird the leverage necessary to hammer through wood.

Pickpeckers most likely evolved from insectivorous coraciiforms similar to todies  or motmots (although dirostrids are considered basal alcedinoids rather than momotoids, they may be closer to motmots than kingfishers).   Many motmotoids probe trees for wood-boring insects, picking away bark with their tiny beaks, and the dirostrid feeding apparatus probably evolved as an extension of this behavior.  

Pickpeckerfoot


Fig 2: Zygosyndactyl foot

    Another interesting feature of the dirostrids' physiology is their pedal structure.  Pickpecker toes are arranged in a unique 'zygosyndactyl' configuration, with digits one and four fully reversed and opposed to digits two and three, which are fused at the first joint.  Zygosyndacylity is no doubt a product of the kingfishers'  zygodactyl feet evolving in convergence with the syndactyl  feet of the woodpeckers of Home Earth.  The zygosyndactyl arrangement gives a pickpecker a firm hold on its vertical perch, and gives the bird the leverage necessary to hammer through wood. 

Pickpeckers most likely evolved from insectivorous coraciiforms similar to todies  or motmots (although dirostrids are considered basal alcedinoids rather than momotoids, they may be closer to motmots than kingfishers).   Many motmotoids probe trees for wood-boring insects, picking away bark with their tiny beaks, and the dirostrid feeding apparatus probably evolved as an extension of this behavior.  

Banana-Beak Pickpecker (Hemignathoides magnus)

Pick1

Banana-Beak Pickpecker, Hemignathoides magnus (Northern North America)

With a wingspan of over a meter, the banana-beak pickpecker (Hemignathoides magnus) is the largest of the North America dirostrids This species, with its wide wings and blocky, almost kingfisher-like appearance, favors the cold, old-growth forests of northern North America. Here, the trees are large and thinly spaced, and there is little undergrown to impede the movement of this large bird as it searches for grubs below the bark.

Like most pick-peckers, the bananabeak has no call, but these birds can easily be identified by the noise of their hammering.

Black-Chinned Pickpecker (Dirostrornis bicolor)

Pick4

Black-Chinned Pickpecker, Dirostrornis bicolor (North America)

The black-chinned pickpecker (Dirostrornis bicolor)  is the most common and probably the most recognizable dirostrid species of North America.  This species can be found throughout the deciduous forests of North America, and varies little from place to place.

Green Pickpecker (Compsorostronis formosus)

Pick3

Green Pickpecker, Compsorostronis formosus (Central America)

The green pickpecker (Compsorostronis formosus) is the smallest of the dirostrids, with a wingspan of about ten centimeters.  These dainty birds dwell in the forests of Central America, where they hunt for wood-boring insects as do all dirostrids.

PARABRACHYPTERACIIDAE (Nearcrows)

In the first years of spexploration, songbirds (Passeriformes) were assumed to be present in Spec, and any crow-like birds that were come across were listed as crows. Then it was discovered that lots of so-called passerines were in fact something totally different: they were usually poisonous, grew exceedingly slowly, had weird palates, and possessed the distinctive enantiornithine shoulder configuration. But the crow-like species are not tweety-birds. Close investigation revealed that they weren't songbirds either, however. Instead, the nearcrows, as they are now called, share numerous detailed similarities with our timeline's ground-rollers and cuckoo-rollers, as well as with the kingfishers of both worlds.

Black Nearcrow (Parabrachypteracias palaearcticus)

Originally dubbed "p-Corvus paracorone", the black nearcrow (Parabrachypteracias palaearcticus) is a common sight in the temperate open areas of Eurasia, especially on forest margins. It has bright ultraviolet plumage, a grey beak and grey feet, and eats basically everything, from seeds to fruit and insects to carrion. Females usually lay 3-6 eggs every spring in a nest in a tree or bush, and bred by the female for some 18 days.

American Nearcrow (Parabrachypteracias nearcticus)

A very similar species, the American nearcrow (P. nearcticus), lives in the middle latitudes of North America.

p-ALCEDINIDAE (Kingfishers)

UNDER CONSTRUCTION

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