Rosa Rubicondior: Refuting Creationism - Another of Those 'Non-Existant' Missing LInks

Alnashetri cerropoliciensis

Illustration provided by Gabriel Díaz Yantén
Universidad Nacional de Río Negro.

Analysis of 90-million-year-old fossil rewrites history | University of Minnesota

Many creationists believe the Theory of Evolution is primarily about fossils and that it predicts every stage in the evolution of a species should be present in the fossil record. From this misunderstanding comes the claim that any “missing link” falsifies the entire theory. The fact that palaeontologists have discovered yet another of those supposed “missing links” will therefore cause another bout of cognitive dissonance between what reality shows and what creationists insist reality ought to look like.

Creationists also traditionally deny that dinosaurs are evidence of an ancient Earth and of a mass extinction event 66 million years ago. Instead, they claim dinosaur fossils are normally found in sedimentary rocks because they were killed and buried during the Biblical Flood. This specimen, however, was rapidly buried and preserved by an advancing sand dune — something that is difficult to reconcile with the idea of a catastrophic global flood.

Its discovery was announced in a paper in Nature by a team co-led by University of Minnesota researcher Peter Makovicky and Argentinian colleague Sebastián Apesteguía. The paper describes the discovery of the complete skeleton of Alnashetri cerropoliciensis, a 90-million-year-old small dinosaur that fills an important gap in our understanding of where this group of dinosaurs originated and how they spread across the world.

Alnashetri belonged to a group of dinosaurs known as the alvarezsaurids, later members of which were characterised by their short, stubby arms and small teeth. Alnashetri, however, had longer arms and larger teeth, yet it was one of the smallest adult dinosaurs ever found in South America, weighing only about 4 pounds (around 2 kg). These primitive features and its small size show that the group became small before evolving their characteristic reduced arms and teeth. At 90 million years old, the fossil also suggests that the group originated on the supercontinent Pangaea before it fully fragmented, meaning their later global distribution reflects continental drift rather than migration across oceans.

The Alvarezsaurids – Tiny Specialists Among the Theropods. Alvarezsaurids were a group of small, lightly built theropod dinosaurs that lived during the Cretaceous Period, roughly 100–66 million years ago. Their fossils have been found in South America, Asia, and North America, showing that the group achieved a wide geographic distribution before the extinction of the non-avian dinosaurs.

They are especially notable for their unusual forelimbs. In most later alvarezsaurids the arms were extremely short but very powerful, ending in a single large claw. The other fingers were greatly reduced or absent. This strange anatomy puzzled palaeontologists for years, but it is now widely interpreted as an adaptation for digging into termite mounds or ant nests, suggesting that many alvarezsaurids were specialised insect-eaters. Their jaws also contained small, simple teeth suited to this kind of diet.

Despite their unusual appearance, alvarezsaurids clearly belong within the theropod dinosaurs—the same broad group that includes famous predators such as Tyrannosaurus and Velociraptor. More specifically, most analyses place them within Maniraptora, a branch of theropods that also includes birds and their closest dinosaur relatives.

Maniraptoran dinosaurs share several anatomical features, including long arms, flexible wrists, and often feathers. Many members of this group—such as dromaeosaurs (“raptors”) and troodontids—show increasingly bird-like characteristics. Because of these shared traits, birds are now recognised by palaeontologists as living dinosaurs, descended from small feathered theropods.

Alvarezsaurids appear to be part of this same evolutionary radiation. Although highly specialised, they share skeletal features with other maniraptorans, including aspects of the pelvis, hind limbs, and wrist bones. Some researchers have even suggested they may be closely related to early birds or their immediate relatives.

The early members of the group looked quite different from the later forms. Primitive alvarezsaurids, such as Alnashetri, retained longer arms and more typical theropod teeth. Over time, the lineage evolved the extreme forelimb reduction and specialised claws seen in later species. This evolutionary sequence helps palaeontologists reconstruct how unusual anatomical features can evolve gradually from more conventional structures.

The discovery of early members of the group therefore helps clarify both when alvarezsaurids evolved and how their distinctive anatomy developed. Like many dinosaur groups, they illustrate the broader pattern of evolution within theropods: diversification into a wide range of ecological roles, from giant predators to tiny insect-hunters—and ultimately to the birds that still live today.

The discovery and its significance are discussed in a University of Minnesota news item and in an article on the University of Minnesota College of Science & Engineering website.

‘Tiny’ dinosaur, big impact: 90-million-year-old fossil rewrites history
New study says Alnashetri originated when the continents were still connected as the supercontinent Pangaea
MINNEAPOLIS / ST. PAUL (02/25/2026) — A team co-led by University of Minnesota Twin Cities researcher Peter Makovicky and Argentinean colleague Sebastian Apesteguía has identified a 90-million-year-old fossil that provides the “missing link” for a mysterious group of prehistoric animals.

The study, published in the peer-review journal Nature, details the discovery of a complete skeleton of Alnashetri cerropoliciensis. Alnashetri belongs to a group of bird-like dinosaurs, known as alvarezsaurs, that are famous for their tiny teeth and stubby arms ending in a single large thumb claw. For decades, they have remained a mystery because most of the well-preserved fossils were found in Asia, while records from South America were fragmented and difficult to interpret.

In 2014, the almost complete fossil of Alnashetri was discovered in the northern part of Patagonia, Argentina, at a site that is world-renowned for its exquisite Cretaceous fossils. The species was originally named a few years prior based on fragmentary remains, but this newer, more complete specimen allowed the team to finally map the group's strange anatomy. The team spent the last decade carefully preparing and piecing together the fossils to avoid damaging the small bones.

Alnashetri was rapidly covered by an advancing sand dune that preserved it almost intact for 90 million years.

Photo provided by Peter Makovicky, University of Minnesota.

Going from fragmentary skeletons that are hard to interpret, to having a near complete and articulated animal is like finding a paleontological Rosetta Stone. We now have a reference point that allows us to accurately identify more scrappy finds and map out evolutionary transitions in anatomy and body size.

Professor Peter Makovicky, lead author.
Department of Earth and Environmental Sciences
University of Minnesota
Minneapolis, MN, USA.

The discovery of this nearly complete skeleton opens up a new understanding of how its lineage evolved, shrank and spread across the ancient world.

Unlike its later relatives, Alnashetri had long arms and larger teeth. This proves that some alvarezsaurs evolved to be tiny long before they developed these specialized features thought to be adaptations for an "ant-eating" diet.
Microscopic analysis of the bones confirmed the animal was indeed an adult of at least four years old. These animals are not just among the tiniest non-avian dinosaurs, but they never get any bigger—the largest species are the size of an average human, very small for dinosaurs, and Alnashetri itself weighed less than 2 lbs making it one of the smallest dinosaurs known from South America.
By identifying previously found alvarezsaurs fossils in museum collections from North America and Europe, the team proved these animals originated much earlier than expected when the continents were still connected as the supercontinent Pangaea. Their distribution was caused by the breakup of the earth's landmasses, not unlikely treks across oceans.

The well-preserved fossil was recovered from the La Buitrera fossil area, a site that has yielded other scientifically critical animals, including primitive snakes and tiny saber-toothed mammals.

University of Minnesota Professor Peter Makovicky uncovers fossil bones at the La Buitrera fossil area.

Photo provided by Minyoung Son, University of Minnesota.

After more than 20 years of work, the La Buitrera fossil area has given us a unique insight into small dinosaurs and other vertebrates like no other site in South America.

Sebastian Apesteguía, co-author
Área de Paleontología
Fundación Azara
Universidad Maimónides
Buenos Aires, Argentina.

Their work is far from over, as the scientists continue to discover and study fossils from the same area where they discovered Alnashetri.

We have already found the next chapter of the alvarezsaurid story there, and it is in the lab being prepared right now.

Professor Peter Makovicky.

In addition to Makovicky and Apesteguía, the international team included Jonathan S. Mitchell from Coe College in Iowa; Jorge G. Meso and Ignacio Cerda from Instituto de Investigación, Universidad Nacional de Río Negro and Museo Provincial; and Federico A. Gianechini from Instituto Multidisciplinario de Investigaciones Biológicas de San Luis.

Publication:
Makovicky, P.J., Mitchell, J.S., Meso, J.G. et al.
Argentine fossil rewrites evolutionary history of a baffling dinosaur clade.
Nature (2026). https://doi.org/10.1038/s41586-026-10194-3

Abstract
Alvarezsauroids are an enigmatic clade of predominantly small-bodied theropod dinosaurs that are known mainly from the Jurassic to Cretaceous periods of Asia and South America^1,2,3. Late Cretaceous alvarezsauroids possess specialized forelimbs adapted for ^4,5, minute supernumerary teeth and heightened sensory capacities⁶, and are interpreted as myrmecophagous. They are hypothesized to exhibit evolutionary miniaturization coupled to their dietary specialization². Fragmentary South American taxa are traditionally arrayed as a paraphyletic grade with respect to the Late Cretaceous Asian subclade Parvicursorinae^2,3, invoking dispersal to explain their disjunct distributions. Here we describe a skeleton of the alvarezsauroid Alnashetri cerropoliciensis⁷ representing to our knowledge the most complete and smallest South American taxon to date. We also recognize two alvarezsauroids among historic taxa from the Northern Hemisphere. Phylogenetic analysis recovers Alnashetri among basal non-alvarezsaurids, rendering South American taxa polyphyletic. Combined with the new taxa recognized here, our biogeographical analyses infer a Pangaean ancestral distribution for Alvarezsauroidea, with vicariance dominating the early history of the clade. The early branching position of Alnashetri among larger-bodied relatives revises best-fit models of body size evolution in alvarezsauroids—we find no support for evolutionary miniaturization but, rather, find support for repeated evolution within a narrow body size range.

Makovicky, P.J., Mitchell, J.S., Meso, J.G. et al.
Argentine fossil rewrites evolutionary history of a baffling dinosaur clade.
Nature (2026). https://doi.org/10.1038/s41586-026-10194-3

© 2026 Springer Nature Ltd.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

What makes discoveries such as Alnashetri cerropoliciensis so valuable is that they help fill in the fine detail of evolutionary history. Evolutionary theory does not predict that every intermediate form will be preserved, but when fossils like this are found they often reveal exactly what evolutionary biologists expect: a mosaic of primitive and more specialised features showing how a lineage changed through time. In this case, the fossil shows that the extreme forelimb reduction seen in later alvarezsaurids evolved after the lineage had already become very small.

Far from undermining evolutionary theory, finds like this strengthen it. They demonstrate how major anatomical changes arise gradually within a lineage and how the evolutionary history of a group can be reconstructed from fossils found on different continents. The distribution of these dinosaurs also fits perfectly with what we know about plate tectonics and the breakup of ancient supercontinents.

As usual, the real conflict here is not between the fossil evidence and evolutionary biology, but between the evidence and the claims of creationism. The geology, the anatomy, and the evolutionary relationships revealed by fossils like Alnashetri all point to a deep history of life on Earth stretching back tens of millions of years — a history that simply cannot be reconciled with a recent global flood or a young Earth. Each new discovery adds another piece to that immense and fascinating puzzle.

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