In evolutionary theory, organisms that possess traits that bridge the gap between two different groups are referred to as “connecting links.” These species provide as proof of the groupings’ shared evolutionary history and show how they could have descended from a common ancestor.

One well-known illustration of a connecting link is the dinosaur Archaeopteryx, which resembled a bird and lived around 150 million years ago. Archaeopteryx features feathers and a long, bony tail, as well as traits from both avian (bird) and reptile animals. This makes it a crucial piece of proof supporting the idea that tiny, feathered dinosaurs gave rise to birds.

The mammal-like reptiles, a group of reptiles that existed during the Mesozoic era and possessed several traits similar to those of mammals, including fur, nipples, and the capacity to control their body temperature, are another illustration. These animals demonstrate how mammals may have descended from reptile-like ancestors and offer proof of the evolutionary link between reptiles and mammals.

Because they demonstrate the shared ancestry of many groups of creatures and assist to fill in the gaps in the fossil record, connecting linkages are crucial to evolutionary theory. They also aid in illuminating the evolutionary process and demonstrating how species have changed over time.

Overall, connecting links play a crucial role in understanding the evolution of life on Earth and demonstrate how species are related through a common ancestry.

Examples of Connecting Links


Bacteria and Fungi


Protochordates and Vertebrata

Archaeopteryx (Bird)

Birds and Reptiles

Balanoglossus (Hemichordate)

Echinoderms and Chordates

Chimaera (Rat or Rabbit fish)

Bony and cartilaginous fishes


Fish and Land vertebrates


Coelenterates and Platyhelminthes

Club moss

Bryophytes and Pteridophytes


Pteridophytes and Gymnosperm

Duck billed platypus, Spiny ant eater

Reptiles and mammals

Euglena (protozoan)

Plants and animals

Gnetum (gymnosperm)

Gymnosperms and Angiosperms

Hornworts (moss)

Protista and bryophytes

Latimeria (fish)

Fish and Tetrapods (amphibians)


Protista and fungi

Neopilina (Mollusca)

Annelids and Mollusca

Ornithororhnchus (Duck billed platypus)

Reptiles and Mammals

Perpaturus (walking worm)

Arthropods and annelids

Proterospongia (protozoan)

Protozoa and Porifera

Protopterus (lung fish)

Pisces and Amphibia


Virus and Bacteria

Seymouria (reptile)

Amphibians and Reptiles

Spenodon (living fossil lizard)

Amphibia and Reptiles

Tornaria larva

Echinoderm and chordate

Trochophore larva

Annelida and Mollusca


Living and Non-living

Xenoturbella and Nematoderma (flatworm)

Protozoa and metazoa

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.


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