A recent discussion of the pros and cons for feathered dinosaurs noted that birds and dinosaurs were created on different days. Birds were assigned to Day 5 (Gen 1:20), but the dinosaurs to Day 6 (“beasts of the earth” Gen 1:24 esv). Such a distinction ignores the fact that our modern, scientific taxonomic groups do not necessarily reflect the biblical descriptions given for the creatures made on each day. For instance, if we consider what day reptiles were made, we immediately realize it is a complicated question because there are terrestrial, aquatic, and flying reptiles. The great number of aquatic reptiles could be included in “the great sea creatures and every living creature that moves, with which the waters swarm” (Gen 1:21 esv). The following marine reptiles would be candidates for Day 5 creations: plesiosaurs, ichthyosaurs, and mosasaurs. These three groups include many species and may themselves consist of multiple created kinds.
As can be seen, these two major groups of marine and flying creatures include many reptiles. That means that God created reptilian creatures on Days 5 and 6, since lizards and snakes fall among “the creeping things and beasts of the earth” of Day 6 (Gen 1:24 esv). Spreading animal classes across different creation days occurs also with mammals: flying mammals (like the bat) on Day 5, but land mammals on Day 6. Various organs, skeletal structures, and functions display repetition across class boundaries:
- Egg-laying is found among Day 5 birds and reptiles, but it is also present among some Day 6 reptiles and mammals
- Lungs are found in birds, mammals, reptiles, amphibians, and some fish made on Day 5, but also among Day 6 reptiles, amphibians, and mammals
- Two-legged animals are found among birds on Day 5 and mammals and reptiles on Day 6
- Four-legged animals on Day 6 includes amphibians, reptiles, and mammals
- Warm-bloodedness is found in both birds (Day 5) and mammals (Days 5 and 6)
- Flying (winged) birds, reptiles, and mammals would have all been made on Day 5
The penguin provides a good example of potential ambiguity in its creation day appearance. Although it is classified as a bird, it is not a “flying creature” and is only semi-aquatic, perhaps moving it out of Day 5 into the Day 6 creatures. We violate sound exegetical principles by any dogmatism in attempts to disambiguate the penguin’s creation day entrance. Since we must be careful with a living animal like a penguin, we must be even more cautious in making dogmatic statements about which day God created an animal we only know from fossils.
* Photos: Komodo Dragon, by Jessica McLain with permission; Penguins, licensed through Adobe Stock
 Haynes, “The debate over the classification of Archaeopteryx as a bird,” Answers Research Journal (2022).
 See McLain, et al. “Feathered dinosaurs reconsidered: New insights from baraminology and ethnotaxonomy,” Proceedings of the ICC (2018), pp. 506–8 for more discussion of this topic.
 Leupold, Exposition of Genesis (Baker, 1942), p. 80 includes “amphibians like the saurian of every class and description.”
 None of these groups have yet been investigated with statistical baraminology, although non-plesiosaur sauropterygians have by LePore and McLain, “Which came first, the flipper or the leg? Evaluating the sauropterygian fossil record from a creationist perspective,” Journal of Creation Theology and Science, Series B (2021).
 Sarfati, The Genesis Account, 2nd ed. (Creation Book Publishers, 2015), p. 224 suggests the Hebrews classified creatures according to their mode of locomotion.
 There is good evidence for multiple created kinds of pterosaurs. See, for example, McLain, “New baraminological analysis of ‘basal’ pterosaurs confirms multiple holobaramins,” Journal of Creation Theology and Science, Series B (2022).
 The Greek Septuagint translates both “swarms” and “creepers” in Gen 1:20, 21, 24, 25, 26, 28, 30 with herpeton (“reptile”), perhaps because the translator recognized reptiles to be both aquatic and terrestrial.
 Some extinct amphibians were likely totally aquatic (e.g., Acanthostega, Crassigyrinus, etc.) as are some living amphibians (e.g., sirens).
 Lungfish, for examples, possess both gills and lungs.